Seems like you should be able to just change the 24VDC bulbs for 12VDC bulbs...
My surplus military trailer also had a stand alone parking brake which was neat to have...
Big trailers also come with other requirements... If it weighs a certain weight it must have electric brakes, the hitch of course probably needs to be changed to a regular trailer hitch. Of course if it has electric brakes then it also must have a breakway switch installed and its own 12VDC source to activate the electric brakes if it breaks loose when being towed.
Our trailers require to be licensed and pass safety inspections...
check with your local DMV or DOT to see what you need in this respect in your state.
Anything you need for trailers including wiring and cables , lamps, etc can be purchased from ETRAILER.COM A great place to visit with all kinds of info on all trailers with wiring schematics etc...
Roy Ken