Followup: Well, I bought a relatively inexpensive Induro monopod. I don't intend to use it a lot, so I didn't want to spend a lot of money. It was just fine - nice and light, folded up short. The problem was with my Manfrotto head which does not fold up well and is rather heavy. I use for my 6x7 and my 4x5. On the trip to NYC, the monopod was great, but the head was a giant PITA. I am going to have to get a much simpler and lighter head for it to make it truly portable on such trips. Nonetheless, I was able to get down to 1/60 with RB67 without any loss in sharpness. I even shot a few at 1/30 with extra bracing from a fence.
btw, thanks for all the input, folks!