The car I bought .. the op had started sanding panels and covering with primer. The car is completely covered in surface rust where the op painted the primer. The primer is designed to suck in paint to adhere it to the metal. If no paint comes , that moisture will penetrate and rust.
I do not remember the episode, but on bitchin' rides, they sprayed a car with primer and then the project was shelved for a bunch of years.. when they dug it off their racks, it needed a complete restore again. I have a friend who has had 2 cars sitting outside on rotisseries for 11 years now (long story), he sprayed with one part epoxy. zero rust.
just use regular 2k primer and overspray or completely top coat whenever the time comes.
A friend used regular primer on a project and lost interest.It's been outside for a couple of years and hasn't rusted yet.Are you sure you need epoxy primer.