Come on Carl, it's not really all that critical. Climate wise
I'd say the here in the mid-west we have a balance between the
east and the west, wet at times, dry as a bone at others. I've
blasted bare lots of metal and simply sprayed it with Rustoleum
rattle can enamel paint with no conditioners or even primers.
Had a trailer frame that sat out back of the barn for 20 years
and it was still solid, restored lawn mowers & tractors painted
the same way, stored in the shed and they've lasted even longer
than the trailer without rusting up.
Blast, swab & rinse with some conditioner, prime with DPLF
primer and paint, that's not all that complicated. That's all
I've done with this truck, ain't no show winner but
for a driver it's plenty good and will probably outlast me.
http://www.pbase.com/dennygraham/image/139199169/largeNow if your looking for a class winner super show worthy paint
job then you'll probably consider all the rest of the stuff,
like cleaners, conditioners, epoxy primer, sanding sealers,
base coat clear coat.
DG