Obviously, that's not the questionable part... what about the COASTER BRAKE?
I think it will work. The spring load shouldn't change pedaling forward or in reverse. I know they use them on frames like mine built for a derailleur, when they are switching to fixie... and I think locking your feet and pedaling back to activate the coaster would amount to the same forces as far as the tensioner goes. Either way I'm going to find out, my dropouts don't have any adjustments in them so I ordered one...
Carl.