POR15 is amazing stuff but it will not make seized/rusted bolts any easier to get out. That is the primary reason I am so militant about advising NO rust if you plan to keep it for any length of time.. the savings just aren't worth the future work required to get things loose for maintenance/upgrades.
And the clean ones are out there! Just need to be patient.
Meh. You southerners and desert people. <I mean that in the kindest way> If there is no rot just some surface rust you can stop it for the long term. Decades. You just have to put the work in and if you can save $$ with a little rust so why not. I am not saying a rust bucket is a good thing. Rot is bad. But if you have to scrub off a little flaking and do a little prevention what's the big deal? Sure you might have to replace a few bolts but that's fun and lets you memorize the size and thread count for every bolt you replace. And you will learn life skills like how to crack a seized bolt with care. It's not only rust that can seize a thread.