I don't see a way to make it happen cause it would need to be hard coded in reaper itself, but try on the reaper forums there are some guru wizards there, maybe they can sort out something.
I personnally programed the F button to be "delete what i have recorded / go back to where I was / record again" so that i hit one button the "f" whenever i'm not happy and record again. When i am, i hit spacebar. It's quite simple that way ! So that I have R to record normally, F to record with this behaviour, and they are close to each other on they keyboard as well.