My solar controller is located in the inverter box on the opposite wall as far away as possible from the inverter. That's the way it came when I purchased my rig used. Ironically, my RV is in the shop getting additional solar and a second controller installed. Yes, it does get warm in there, but it has not been an issue and I live near Phoenix. I figure, that's how the factory wired it so that must be the best place for it. Good luck.
2014 Renegade Classic, 45', Freightliner Cascadia 126
Cummins ISX15 with 13 speed Eaton auto shift
1999 Jeep Wrangler toad