Sig Lite-Coat should work fine with your silk. I use it all the time with Jap tissue. There it is pretty much non-shrinking. I find I have to shrink the the tissue with alcohol before doping. There is also a retarder available, I beleive, from Sig.

You should build a simple flat square out of scrap and cover it and experiment. This is a great way to proceed with new covering methods. also check out the forum at smallflyingarts.com, there are some master bone coverers over there.

-Derek