*One thing I found is most RV windows don't have finish trim rings inside when bought off eBay or the salvage yards. So simply run upto your big box store and buy some cabinet finish screws. They offer black, have large heads with a aggressive thread. I drilled and screwed the window in from the outside aluminum lip.
The inside trim ring was made by 1 x 3 wrapped with a tan fabric. The corners are cut at a 22.5 degree angles to mimic the rounded window corners.
Finished project for Saturday..