I have some super strong magnetic strip material. I may concider removing the studs and epoxy it to the backs of the emblems. No holes for rust, and i can change em out at will.
Depending on how good your magnets are, you may consider gluing a piece of thin fabric/felt/paper to the back of your emblems so that they can be attached/removed/adjusted without scratching up your paint. You can trace the emblems and use an exacto to make the felt or whatever just right.