Opinions please??

I have a new project, a 79 Chevy luv that i already fixed most of the rust on, which wasnt bad at all. I am waiting to do any bodywork or anything but rust repair until after school, so I'm not going to do any media blasting yet. My question is that there is some rust on the bottom side of the bed rails that I would like to try to fix. I cannot get a grinder or anything up there. What are some opinions on what I should use, i know there are a lot of different "rust-stop" sprays out there, but do any of them work? Im not really a believer in that type of fix, but all im looking for is something to save it for about 2 more years of sitting.Thanks for the help!