Your 10mm eyepiece is the only one that will be fully illuminated.

I recomend diagraming your system on paper (wraping paper, inside of present wrap, etc.)

Assume a good eyepiece with fair APOV of 60° for your area of maximum illumination. Use that for the plane of focus and draw lines from each edge to same edge of mirror. Mark off focuser spacings and other distances to determine size and position of secondary.

Two things I always say: Diagram it and maybe two secondaries are in order. If you had another scope then the small 100% illuminated field would be acceptable for planetary work but for an only scope, I would want to be able to access wider and brighter fields also. It would be nice to use a 56mm 2" eyepiece.

Have Fun,
-Rick