.. you've almost described what I'm planning on doing next weekend ..
Although I'm not a pro, a very good friend (my usual photobuddy for day trips) is getting married on Saturday. The bride's uncle is a pro and will be taking shots of the day.. but as I'm the only eedji-it shooting film that he knows he's asked if I would bring the RB67 Pro S. Which is, incidentally, equally suitable for your plans as the RZ67 - although I haven't yet tried remote triggering flashes it should be possible via the PC socket on the lens and an adapter.
I wasn't planning on presenting the Polaroid (Fuji FP-100C) test shots to the bride due to the frame coverage issues (see here), but I will show them to the couple and they will be welcome to keep them.
I'm not sure if everyone that's replied is familiar with an RB67?
Switching backs between 120 film and Polaroid is quick, quicker than the FP-100C will self-develop. One latch drops off the Polaroid back complete with P-adapter and you can drop the 120 back (complete with rotating back adapter already attached) straight back on again.
You should have a darkslide for every back anyway. It's pretty much compulsory.
My planned load-out for the day.. RB67 Pro S, 90mm C, 180mm C, 2x 120 backs, 1x Polaroid back.. Kodak Portra 160 and 400, Fuji FP100-C and FP-3000B, tripod.
The biggest issue with the Polaroid back and the RB67 is the lack of interlocks.. it's easy to get reliant on the camera not firing of things aren't right. My current fix is 6" of bright red ribbon as a "remove before flight" tag on the handle of the Polaroid darkslide. Incidentally, the Polaroid back uses a unique darkslide that's not compatible with any of the other RB67 backs.