On Tue, 28 May 2019 10:21:33 -0700 (PDT), Lee Nowell
wrote:

snip

I have been recommended to
- wire brush most of the rust off
- use Kurust on what's left
- cover it all in waxoyl

Any other / better suggestions?

Depending on the level of 'rust' and how 'stripped' the trailer is,
use a flapdisk thing (in an angle grinder), along with a wire brush
(had / drill) to take it back to bare metal and re-paint with a decent
red / grey oxide type primer and a couple of coats of a chassis paint
(or Hammerite if you have some to use up).

Cheers, T i m

p.s. Sand blasting then galvanising would be the *best* solution. ;-)