In my previous employment I I treated a lot of mold damaged dwellings. There is no one way to treat it. It's case by case. The first thing to remember is that mold only grows where it is damp. Remove anything and everything that that can be removed without damaging the trailer. Put it all in a place where it will stay dry and won't warp from having pressure in odd places.open the windows
and vents. Set fan to dry the interior completely. This will stop any continued growth The hardest thing to dry out is the floor. It's l likely to get dry root if you can't dry it out. Others may have suggestion, but I would consider boring multiple holes through the fiberglass into the plywood under the trailer. You can plug them later. Use a shop vac with a hepa filter to vacuum all of the carpeted surfaces. you can kill all types of common molds with a solution of 3/4 cup of bleach to 1 gallon of water. This is likely to discolor fabrics. No stronger or the mold will harden it's spores. Use the solution on every surface you determine won't be damaged. So many people are overly worried about mold. If you have notice most of the hype about mold has gone away because attorneys were losing cases. In most cases, especially in the South, the ambient mold count is as high outside as it is inside and most people aren't sensitive to mold at those levels.
There is an alternate proven method of killing common molds I have used, but I don't know how you would use it in a fiber trailer. 145 degrees for 30 minute. some molds are as low as 125 degrees for 25 minutes.