Yup any bellows-focusing camera like the RB or a 4x5 will work well. I have done some macro with a Nikkor 120 AMED on an old crown graphic, using a closeup diopter. Fun combination and very light and easy to take into the field. The RB is much heavier but for macro that is somehting that you quickly learn to love: stability! Also the nice thing about the RB is that you can use a metering prism so then you can just forget the bellows factor calculations.

Let me also suggest that a good diopter on the hassie may be a very simple solution. Especially if you are stopped down to f/22 or more then there is little (if any) performance penalty.