Jay, the only thing I would say, is to put something like wax paper or
mylar on the inside and tape it in place. The adhesive on the duct tape
may inhibit the cure of the RTV. You may even find a clear acrylic
compound that you can put in there. Also, if you place the mylar on the
outside after you are complete you may get it to feather quite nicely to
the original material.

Actually, I think my A&P said he was going to use a clear epoxy of
some sort, as RTV will "weather" over time and eventually fail.

I'll post how it comes out...
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"