I can't go for HPS or anything "fancy" quite yet

Sounds like one small switchable HPS ballast and some ventalation might be less fancy than all the stuff you are trying to figure out with these flouros.

Some people here are probably familiar with my opinion about this and I don't want to start any arguments, but please, I'm begging you, for the love of God and the sake of your harvest, consider doing it right next grow.

Good luck.