Just duct tape some plastic across the back of the panel ,Heavier than a trash bag should be fine .it's just a little prevention and will help with air intrusion don't cut holes for the handles just push the handle studs thru the plastic , I have the chrome countersunk washers if you need them I can throw some in an envelope . The only thing about the design on those panels is potential wear from the window crank hitting the raised material when lowering the window . maybe you could draw your own design and have him make them for you ? Any auto upholstery shop could but not for $75.00
Door board $18.00
Vinyl $ 5.00
glue $ 2.00
foam $ 5.00
labor $45.00 Total $75.00 = cheap price , He lives in Mn it's a good shop time filler ebay project
Total shop expenses when supplies purchased wholesale