Hello jimmykins,
Congrats on your purchase! Living in Southern Arizona I completely understand.
After purchasing my unit (XP), I parked it directly in the sunlight (windshield facing the sun)and let it sit for several days. I found that the weather stripping would warm up and conform the adjacent surface. Now of course I don't have the rear glass so maybe someone else will chime in.
I also found that during assembly the "Gump brothers" at the dealership misaligned the clear plastic and lower black plastic leaving open gaps above the rear seats. I disassembled the whole thing, realigned and added a nice piece of weather stripping.
Additionally, I added a small amount of weather stripping to the front corners of roof where I notice a small amount of water came in when washing the unit.
Hope this helps!