Worried about heat/space

I am about to start my first grow in a 2 sided cabinet. Measurements are 19.5" x 22.5" x 49" for each side (~3 sq. ft.) I was thinking of putting in a 250w MH/HPS switchable light and using only one side for now.

Will this produce too much heat? I'm hoping not to have to cut any holes for ventilation fans.

Also, I'll have 42" of vertical space under the light. Is that enough space since the light will have to stay far enough above the plants during flowering so not to burn them?

Any advice would be greatly appreciated.

So one plant on each side...

Height sounds ok, you can bend them or stay with a short indica. Seems a little tight side to side.

Could be done though.

You would have to have some fans though IMO.

Especially with that light, I have fans with my floro grow box.

My lights (well ballasts) need cooling.

I decided to go with 250w CFLs for now. Going to switch bulbs from veg. to flowering. Once I get some experience I may do a SCROG.