Here's a few tips on paint removal...(yes I speak from experience)
First, pressure wash everything. Second Wash by hand the entire trailer with
a solution of Tide and Water in a bucket mixed 1 part Tide, 4 parts Water
Let dry completely.

Purchase any of the commercially available "Methyline-Chloride" Paint
strippers, I prefer the ones that are called "Aircraft Paint Remover"

Use a well ventilated area, as this crap stinks, and also use heavy duty
chemical resistant gloves as it burns the skin...what I do, is to purchase a
roll of painters masking plastic, it's 4 mils thick. I lay that under the
entire trailer or plane in my case....spread out enough so that you can wrap
the entire trailer....I go like crazy on a hot day putting the paint
stripper on and as soon as I have the whole thing covered LIBERALLY...( only
time you'll hear me use the word liberal by the way) Then wrap the plastic
around the trailer and tape it in place for a few hours...sit back with a
beer on your favorite lawn mower....and leave the crud alone till it's
dry....mostly you'll have large flaked areas which can be scraped easily
off....then you pressure wash the more tenacious stuff...and then you go
back and treat the clingy areas again....generally I can do an airplane in
two days with one helper...try to catch all the nasty paint crap in the
ruined plastic wrapper and discard of that once dry in an appropriate
method...

Easy huh...pressure wash, tide wash, stripper on...scrape, pressure
wash...and dispose....then you need to Alodine 1200 the entire
surface...then use a good "metal etching" primer ( I prefer Montana
Products) and re-paint the whole thing and WHITE....is really the only
choice....

Good luck...happy stripping!!

Steve Hill