I made a little diagram and checked that math, looks right on. I have only one question, can you get servo arms with any amount of offset? It seems that there are only a few options out there.
ORIGINAL: sillyness
I have 2 of the 35% RCBlimpPro tailwheels and I can indeed vouch that they are the best tailwheel I've ever seen. They aren't the ABSOLUTE lightest (a very close second), but then I've broken 4 of the lightest ones (you know which ones I'm talking about). The RCBlimpPro is indeed bullet-proof and I love it.
Anyway, try running that formula I gave you when using the crossed cables... setup a test rig if you want. You'll have no slop. Bless Pythagreas (sp?).