You can quite easily adapt rb/rz lenses to LF. Look up Erie Patsellis on APUG, he has a nice solution which allows you to trigger the leaf shutter. My method is a bit simpler, I just hand shutter; all I do is fasten the lens onto a makeshift 1/8" thick lensboard with a big hole in it... I use a rear lens cap to attach the lens to the board. Works like a charm.

Coverage... there is quite a lot at close focus. I have done some 5x7 macro with some tilt using an rz 110/2.8 lens. Even at infinity focus, you can fill most of a sheet of 4x5 film with these lenses. But for portrait / closeup etc. you can easily fill 4x5. (Note: Per Volquartz sometimes uses a 35mm lens for LF macro...)

The main thing is that the rb/rz lenses are quite heavy and will put a good deal of strain on a camera. I have an all-metal 5x7 rittreck that stands up well, it's very robust. A cambo would probably do well. But a wooden field camera... don't try to put an rb/rz lens on that. You'll probably break something.