Painting suspension/frame parts??

[MASTERBrian]

I know this has likely been beat worse than a dead horse on forums all over the internet, but I have to ask.....

I'm trying to go through and clean up as much of the underside of my 1960 suburban as I can. I'm not looking for a show stopper and it's doubtful it'll ever be in one. I'm just trying to get it sealed up so that the rust that is there doesn't progress any worse, until I can get in and repair properly. I want to make things nicer, while I have the engine out and while I'm doing the drop on the rear and front along with the disc brake conversion. I'll also likely be dropping the fuel tank to clean and seal it with POR-15 tank kit.

I've painted the firewall and inner fenders with Satin Black Rustoleum spray and primer. So far I haven't fixed the floor boards, the body supports or the inner fender rust spots up by the radiator support. Once she's up and running I plan to start tackling any body issues such as those as time/money permit. The plan is to leave the original patina look for now as I work from the bottom up and inside out. I know, I know, while everything is apart it's easier, but I also know myself and how these projects go. If you try to tackle everything I'll never get her on the road, which is the reason I got her.....

My understanding is once POR-15 is down, it's a mess getting it back off and therefore working the areas where it's been applied will be a mess. I hear bolts don't like to come out, etc....in fact I accidentally got some on a valve cover bolt while painting the engine and had to take a vise grip and torch to it to get it out without braking it. I'm considering applying their floorpan kit to my floor, but most likely I'll just buy and replace, really depends how bad they are when I get to them.

With that, what does everyone recommend? Should I get Rustoleum etching primer, brush what I can and spray can what I can't brush and then paint it the same way? Or is the POR-15 far superior? I've read both sides of this debate, but my thought is since I don't want to run POR-15 through my paint gun, I can't easily apply it to the nooks and crannies. I think they might have a spray but it's expensive as well and what will that do to rubber bushings and such? I'm also concerned how easily everything will come apart later if I use it to coat stuff. At some point fenders might have to come off, I have to unbolt the body supports to replace those, etc....

I'm also curious what everyone does to the back side of sheet metal, like fender wells, etc. Rubberized undercoating after painting, just paint, bed liner spray/brush, ???

The Rustoleum primer seems to be a rust neutralizing primer as well, so in the areas I can't reach with a brush/wire wheel, I'd think I'd be decent and I'd have matching parts.

***I'll add, I have POR-15 cleaner/degreaser and a bit of metal prep (I'll likely buy more of it or I hear Home Depot has a great product as well, and use that prior to any painting.