A good aluminum screen fabrication company can probably replicate the original screen. Here in Florida, there are many such enterprises due to the number of screened rooms, sun porches, etc. ...May not be the case where you live.
You may have to take the RV to their location for measurement, or if you have any screen in your coach which is interchangeable, that may suffice for the measurements.
Best of luck in your pusuit...
Jim and Fran in Central Florida
1989 Country Coach Sedona Mark V
Turbocharged Detroit Diesel 8.2L "Fuel Pincher"