I am thinking of sanding a bit more to get everything smoothed out then prepping and painting instead of taking the both trunks and interior down to metal in every nook and corner... how bad is it to get sanded but not bare metal everywhere.

i think i've gone overboard trying to strip these areas to metal since i'm not sure what is necessary or ENOUGH prep before painting over it all again.

i keep trying to remind myself that it will mostly be covered in carpet anyway... but i'm anal and a perfectionist... i just think its costing me wasted time and i'm tired sanding.

~700 to have a car media blasted? maybe its time to drop that coin vs sanding for an hour or two a night.

any walkthroughs on what your trunks/floors looked like before, during prep, before por15 and after and then after paint??? how much irregularities in the surface (old paint etc.. undernieth) shows after paint?

Here in Cali they want $1,300.00 to blast mine, not so bad if you look at it like

that.

As on the can, the stuff sticks best to rusted surfaces. If you make it shine, you will need to etch the surface for the paint to stick to it. I'd say take all the flakes off until you hit the last layer of rust and 40 grit sand it until you start to hit metal. Clean with some MEK and paint.

POR 15 will stick to most stuff, including old paint. The issue is that if the old paint is not stuck to the base metal real well, the whole thing can lift, i.e. separate at the metal/old-paint interface. But if the old paint is adhering well, and it's a hidden area where the extra thickness of the old paint layer is not an issue, you can leave it if you wish.
YMMV

Check out Zero Rust... works a bit better then POR-15. Also it won the corrosion test when painted side by side POR-15 and Zero Rust on dock pillings subjected to tidal flow and salt water after 1 year.

And no, you don't have to go to bare metal. If it has good factory paint (and no rust issues under that paint) that area can just be degreased, lightly sanded, then painted over. Check out the professional PPG degreasing agents for prepping existing paint prior to any body work. I've been reading the forums at autobody101.com and finding lots of good info.

I've used Zero-Rust with good results. It's ALOT cheaper than POR15 too!