Im facing a nearly identical situation. Im going to do a project on changes in my hometown. 2 or 3 weeks at least, lots of stomping around with the Domke.
I ended up choosing a Hassy 500c/m with an 80mm and Spotmatic with a Mamiya/Sekor f2.8 28mm, SMC Tak f1.4 50mm and Viv series 1 f2.8 135mm.
My reasoning was along these lines: My Canonet and Yashica GTN both take different batteries I can't get everywhere and are a bear to get fixed. The Spotty can be overnighted to Pittsburgh Camera Service. My Nikon F5 and 3 lenses would be really heavy (even with lithium batteries and the plastic Nikkors). My Bronica GS-1 is just a freaking beast, especially with the 50mm lens in the bag.
Also a big consideration was that I recently (less than a year) had the Spotmatic CLA'd and had the meter calibrated and got a split-image GG, CLA'd back and metered 45deg prism for the Hassy.
Personally, Im so tired of process that I don't give a rats ass about it anymore. Im entirely content to shoot my entire project on Ektar or 400BN or Neopan or whatever as long as I don't have to think about it. If I have to think about much more than subject and exposure I don't want to fuss with it and the Spotty and Hassy are about as simple as any camera can be (this side of a Brownie).
I will keep a Strobist kit (double fold umbrella, Viv 285HV, pair of Wizards) in the car but I'm betting they stay there.
The only bit of new gear I'm allowing myself on this are a carbon-fiber tripod and a good ballhead. My current tripod weighs about 7 lbs (seriously, it's a freakin beast). If it can't be done with mechanical cameras I already own, good glass, film and my feet, it ain't getting done.