Mog, Your last sentence re: "...the solution is much simpler"; sorry, I missed something there. What is the "solution" exactly?
I have no real problem with an infinitely large Greater Void, within which our particular ball of aether is but one, of perhaps as many as there are stars in our piece of the universe. Being of human limitations, and knowing it; I find it difficult to place any limitations on what might be in existence. And also I place no limitations on the abilities of the Creative Force, assuming there is one.
As to the "wall or reflective surface"; this is much as in a raindrop, where it supplies its own periphery simply by discontinuity. The raindrop, even tho' fluid, has structural integrity supplied by surface tension and I think, inner bonds as well. I'm missing the word that describes the ability to hold itself together, even as a fluid.
So to get the attributes necessary to provide the properties of electromagnetic waves as I see them, I describe the aether this way: It is a finite ball of taut-elastic, material, Aether-Lines-Of-Force (ALOFs). The elastic tension tends to collapse the ball, but e-m waves, being ordinary mechanical waves propagating through the aether, vibrates the ALOFs against each other. This keeps the ball fluffed out internally, and provides the necessary tension to explain other observations.
So the aether fabric itself, I describe as being in an interposed cube/octahedron arrangement, with the ALOFs following the edges. And the points of convergence at the cube corners are welded. This gives the opportunity for a continuous fabric, that does not have increased center density, as would be the case with LOFs that are universe-diameter long. And it makes the aether fabric of reasonably constant passive-response performance values, although it would seem compressive force from the tension is cumulative toward center, but so is the fluffing force.
That's incidental as far as we're concerned in a very small part of the ball. But it can be significant for astronomical observations, especially Rate of Redshift, where it is seen as non-linear with distance (not linear with Expansion).
In currently popular cosmology, this nonlinearity is erroneously interpreted as Acceleration of Expansion, and awards are handed out for the "discovery".
Definition of Term: The "force" designation means "passive reaction", as with a similar rubber band lattice; but not ACTIVELY supplying some sort of force. The aether is only a passive wave medium, similar to water versus gravity, rubber sheet mass versus elasticity or rope being waved on one end and watching the waves move along it.
This aether arrangement supplies a satisfactory explanatory basis for all observations (so-called "phenomena") of which I'm aware. And also raises and explains questions usually ignored by currently popular Theoretical Physics.
For instance, to address one of your concerns; What happens to e-m waves bouncing around? How do they reflect off the periphery? The e-m waves are (I say) simple mechanical compression / rarefaction waves propagating through the aether in the same manner as sound waves in air (sometimes called "plane waves"). Any graph-paper representations showing transverse waves are actually the density profile of the c/r waves.
So then, the waves are actually distorting the ALOFs in a reciprocating manner, back-and-forth longitudinally, as the waves pass through (not transversely to the side as with a rope or water surface). The wave-kinetic-energy is contained in the compression aspect as it moves progressively through the ALOFs. When the e-m wave reaches the periphery, it stretches the very outside ALOFs out into True Empty Void, then the ALOF snaps back in, re-injecting the e-m energy into the lattice matrix of the aether fabric. Conservation is satisfied.
But waves also wave-disperse as they travel. This is not as with a puff of dust, but rather, it is the elongation of the wavelength. So the General Redshift of Starlight is immediately explained, without resorting to an Expanding Universe. And we see that the universe is most likely in stable orbit about its own center of mass, exactly as our solar system and galaxy.
The latest galaxy distribution charts support this rather than Expansion. There are great walls and voids in the charts, very similar to the star distribution in the arms of our galaxy. Most certainly these charts do not show explosive outward-motion distribution.
Then these e-m waves can wave disperse right down to the Fundamental Resonant Frequency of the taut-elastic ALOFs. This is Ultra-Low, way off the bottom of the usual E-M Spectrum chart. The wavelength has to do with both the tension of the ALOFs and their ultimate cross-universe length (ignoring the welds). I don't know what value this is, but the CMBR frequency distribution seems to indicate harmonics' peaks, and therefore point to the Fundamental.
It is possible that the initial excitation of our ball came from impact with another ball. They would not unite, but rather would bounce off (I say). In this respect they are more like rubber band lattices, than raindrops.
Interestingly, if on a sunny day, one fills a child's circular wading pool with water (one say 3 to 4 feet diameter), and gives it a single kick, then allows the waves to bounce back and forth, the pattern that emerges very quickly, is almost identical to the CMBR distribution.
Waves do not "cancel each other out in destructive interference", but colliding particles certainly do. This is more evidence of light being waves. One cannot shine two flashlights into each other and get a null to darkness.
Wave interference is very misleading the way it is taught. Actually wave energies appear to pass through each other completely unaffected. I say they actually bounce off each other perfectly, and thereby appear to pass through each other. That is; if a small wave and a large wave collide, that portion of the large wave impacting the smaller wave, reflects, and the smaller wave also reflects. It appears to the eye as if they passed through each other. They cannot simply cancel and disappear, because this would violate Conservation.
The bar patterns of interference happen on materials like photo paper, and the energy is absorbed. Where exposure happens, the waves are adding with great disturbance of the photo-sensitive material. Where dark bands happen, the waves have not "destructively cancelled" but rather have transiently bounced off each other, leaving the particles of photo-sensitive matter at that collision point undisturbed.
This is very apparent in a ripple tank demo, where we see the waves "passing through each other", and dynamically nulling where they cancel, but magically reappearing past the null (node) point.
As to the complex math of orbital forces: Mutual shading, with a Permanent Shade reaching out undiminished across the universe, readily explains the unexpected Stars' Orbital Velocities Curve in a Spiral Galaxy, without resorting to the "Dark Matter" that has yet to be detected.