How long of a bend are you wanting to do at one time or can you do like you've been doing and just have something that get those end spots?
I'm one of those people that when there is a problem I get a "hit" that's a mental pic. My mental pic was for " touch up" of those narrow spots and was my old valve spring compressor with an angle iron as the anvil set as a v and 1/4" flat plate welded to the screw side of the compressor edgewise to meet at the bottom v. The plate could be whatever width would clear the sides of formed rib. I'd probably take off the flat washer thing that's swedged to the screw end of my valve spring compressor right now and weld the 1/4" plate to a piece of pipe that could fit tight over end of the screw to give it enough support.
I don't know if any of that makes sense or helps.