G'day mate.
If you are talking about the red paint, it doesn't look like it is stuck very well to the gal sheet. That being the case I would try a hot air gun if you have one. I had to do the same thing on some tack boxes fitted to my old horse float. The paint came of in sheets back to bare metal. The boxes were about the size of your trailer and it only took me a half hour to do it. Come to think of it even if you don't have a hot air gun they are only thirty bucks or so at Bunnings and they are a great tool. Just don't stick you hand in front of it!!!
Get some good advice about getting the new paint to re-stick the gal sheet. It can be tricky. I would use an automotive paint and clear coat in the colour of your bike. It would look great. It sounds difficult but I had never sprayed paint before and I cut some rust out of the sills of my daughters dark metallic green XR6 ute. I took my time painting it and you could barely see where I had sprayed it. Me doing it saved her $700 so I was a hero at least for a day or so.
I have a compressor and spray gun and it is not really difficult to spray paint. I have got also really good finish using spray cans as well but they are expensive.
They absolute key to getting a good spray finish is to build up lots of light coats letting the paint dry for a few minutes between. Don't be tempted to spray heavy (I always am because I am impatient!!) because the paint will run. The first couple of coats will look like you have barely touched it.
Also don't spray when it is hot the paint will flash off before it hits and don't spray when it is too humid the paint finish will be crap. Both of those things are a bit hard this time of year in QLD.
Have a crack at it. If it turns out good you will think you are really flash, if it doesn't well it probably won't be worse than the paint that is already there!
Have a good Xmas.
Todd
