I don't wanna be the black sheep here, but there's a couple things you really need to keep in mind. Is the box 30" tall and you have to minus 5-6" for the light fixtures? And once you transplant, you're gonna have to keep the height of the pot as low as possible. In the end, I'm guessing you have about 20" give or take to actually grow in? And you're not gonna want your plants touching the light, even if it is just CFLs.
As for the temps, yeah you can grow your plants in 85-90F, but I think it really will slow them down a bit. And tbh, idk how you're planning to add stronger lights, your temps are gonna reach 95-100F. And trust me, that'll kill your plants slowly... If you can, get some better ventilation and it should bring the heat down. Or make a passive intake or something. Oh I just saw you have co2. I heard you can have slightly higher temps with it, but idk, adding more lights might be pushing it, unless you can vent it out.
You're gonna want to LST your plants asap. I've seen plants that grew its whole life at a 90 degree angle. It's crazy, so don't be afraid to be aggressive. Once it's kept down, add a scrog, and let it get filled up around 80%. Then once it flowers just tuck them bitches under, cause dealing with height issues suck man =T. Anywho good luck!