Here's two ideas; try a shop that does auto glass or other glass work, we have a local 3rd generation shop that is good, or my solution was to buy a rear slider window from
Scamp that I was able to install in our
Uhaul by slightly modifying the opening. Or just buy some plexiglass and fix it yourself. Well that's three ideas I suppose, but who's counting. Just thought of a 4th idea, google RV
windows, there's a couple companies that will custom make RV windows, I'm working on that now for replacement side windows but don't have a definite solution yet. One place I tried some time ago was Pelland Enterprises and their 41 X 18 window was $600, easyRV windows.com [Atwood] is another place and they have a radius template that you can print out. secure.onedayglass.com will custom cut tempered glass I believe. Probably the most economical solution is to find a stock window that you can make work, but the trouble is that sometimes you can't tell until the old window is out and you have the new one in your hands, which is what happened to me with the side window and I found it wouldn't fit. Bob