The CitriStrip isn't a big deal, I've used it indoors on small projects with no problem. But you're going to want better ventilation for mineral spirits and stain, and probably some dust control for the sanding. Sawdust indoors is a pain.

An electric heater and some "walls" in the garage (hang some tarps or heavy sheet plastic) should make for a warm enough space to keep working. As long as no one is screaming about parking the car outside.....