It sounds like your in the same situation as i am with keeping the buns cool…i like in PA and it can get just as hot here. My bunnys condo is in my room also and when no one is home the AC is not on bc we dont have central air we only have air units that are in the wall. I do leave my celling fan on though when i am gone and also we have an attic fan which is on when know one is home which brings air in from the outside through the windows more. We have two dogs also so we cant have the house being crazy hot.
I would suggest doing the ceramic tiles i have two on the bottom level of my buns cage and when its hot he lays on them, i also put in two frozen water bottles one on the ceramic tiles and one somewhere else that he normally lays. Even thought you may not see him laying against the frozen water bottles they might when your not looking. And even if they dont it will make the ceramic tiles even cooler which will help.
I personally wouldnt be to worried about it, i know i still worry about my bunny during the hot weather but…if you think about it, there are so many bunnys out there who live in outdoor hutches and are in the heat and are fine,(my friend has two farm buns who live outside year round) i know its not right and i would never do it bc its wrong but my mom always tells me that my bunny is KING bc he is living such a great life indoors haha. Hope this helps!