Originally Posted by
davei1980
Am I missing something here? Why not experiment with plastic fenders. They're rust proof and can be quite durable
No, you aren't missing anything I simply pointed out that the reason the OP's fenders were rusting every three months was not the fault of the fenders, but instead improper painting, namely not priming the fenders first. Whether or not the OP replaces the fenders, it is a good thing to know for future projects. It is something I see here fairly often, people painting without priming first, and then having problems.