There are places here that will do that for you, as I am sure you know.
A friend won a nice three horse slant as end of the year high point and had it converted into a two slant plus a nice area with bit of living quarters arrangement in front.
They also made some changes to the paint colors, leaving the lettering with the win as it was.
She said it was not as expensive as she thought such would be, looks sharp and she said it pulled well and she and the horses like it.
Maybe check with your local trailer places first, before tackling it on your own, if you are not familiar with that kind of work?
If you want to do the painting yourself, first try using a steel brush on any rusty spots, best with those attachments to a drill or grinder, then painting.
Paint that advertises it can go over rust covers it fine, but doesn’t really last long before rust shows up again.