You could probably get a very simple strobe setup (light weight light stand, manual flash, simple diffuser/soft box) that will attach to you RB via a PC sync cable. That will restrict ease of movement a bit, but it would give you that extra bit of fill without needing an assistant. You have enough as it is lugging around that RB!
Also, check out the strobist. I'm a young guy too that never had any formal photography training (that actually just got a RB67 to do more portraiture too funny enough!). I found that site extremely informative. Obviously he is doing digital photography, but the theory, gear and practice is general enough to translate to film.