Pete... We have a curtain that has a light weight rod and we paid about $5 for the rod set up.
Here is a similar one... https://www.walmart.com/ip/Mainstays-48-84-Adjustable-Sash-Curtain-Rod/42489119
Since we knew that our fiberglass top had firing strips in it we hung the rod hangers from the ceiling. Also, the four total screw holes needed are so minimal and do not go all the way through the roof because we have the firing strips and the ceiling board (which in our case is about 1/4").
We also have an old closet rod that sits across the front kind of where your tv and two doors are located. When we are in the mood we can drape it from the rod it hangs on over that other one and that allows it to be behind the seats (because ours turn like Catfish's do).
When our curtain was just the old sheet we had hemmed the rod worked very well. We've since made it heavier with a backing of solar material and it still works but we've got to be more prudent in not pulling down when moving it from side to side (no big deal and we've already adjusted).
We also have an rv window shield that easily and quickly hooks onto the visors and blocks the windshield and both passenger and driver's windows as well as reflectix cut to fit all three, as well.
Since we live in our vehicle full-time we have learned that just a privacy curtain was not doing us any favors when it came to heat / cold. There is a huge difference in temperature from front to backside of the curtain when we pull it and even more so when we apply all three options together.
Anyway, hope something in there helped.