When I had originally thought out how the light tray might be designed, I was worried about it too, but given that the lights are small and the top of the light tray is open, I'm not worried about heat at all. Since it is not enclosed it doesn't even need insulation.
I have boxes arriving daily. Outlets, dimmers, wall plates, equipment rack, equipment rack door, rope lights, cotton, 703, HVAC grilles, etc. I have to carry a box or two downstairs every time I come home.
At this point I think the only things I don't have ordered are the doors to the room, the projector, and the screen. The only things I need to still purchase outside of all of that is the wood to make the fabric panels.