Prosper, I just worked on a rusted base edge last night. Used a gummy stone. Its almost like a rust eraser. I followed with side edge sharpening, then one last light pass with the gummy to remove any burr. I have also used diamond files in an edge guide to polish bases as a touchup. I always set my base bevel at .5 to .7 after a base grind, so additional work does not usually result in more than 1-degree. If you can tolerate less base bevel after a fresh tune, I think its a good way to get more distance out of a grind, and leave you some room to work.
I'm certainly not one of the tuning gurus here. It will be interesting to hear some other opinions.