It's hard to get "large format" and "sanity" into the same thread. But all kidding aside, it doesn't seem like the difference between a compact LF system and a typical MF system is all that huge; my 5x7 setup fits in a backpack, soup to nuts except for the tripod, and it's about the bulkiest 5x7 you could ask for (Eastman 2-D).
Development and contact printing in a windowless bathroom is totally feasible, though if you want to keep it usable *as* a bathroom you'll need to do some careful planning. (I've lived in a couple of 2br apartments with two bathrooms, so it's at least conceivable that you could have some dedicated or semi-dedicated space.) I think in your situation I'd probably keep the 5x7 for contact prints, evaluate the eventual condo for its darkroom potential, and then decide whether it makes sense to expand into MF as well.