Theres a back to it tho i see some racks with no backs and no side walls mine has side walls and a back wall 5/8 MDF just wondering thats ok?
Perfectly fine helps maintain a more even heat

and they are a pretty tight fit i might need to put some air holes in the side of the tubs but i just want to make sure this sounds ok i dont want to cook my babies i havent put in the heating system yet funds alittle low right now
put you some air holes if there is no space at the top you might need quite a few. The main thing is to get a good thermostat to regulate you heat with. Temps can go haywire quick and cause loads of problems if you don't have a good control system in place