Great score, great trailer. I went the other way with mine as far as advertising its contents, no stickers, nothing, even peeled off the Haulmark logos..
Watch tire pressure very closely or you can end up with new fenders whne the tire peels off, dont ask me how I know this...
The only weak point I had with my haulmark was crummy tires...Any excuse you get to change the oems to Carlisles do it...
Brake controllers operation will vary based on load...load the trailer , head down the stree and apply the brakes, bumpo the controller unitl you feel the trailer pull a little tiny bit, then back it off a bump or two,should do it but it is variable between all vehicles and trailers, controllers.. Carry a nice bottle jack in the trailer with a mounted spare tire and chocks too.
I would also look for rope light for lighting. The led's nowadays throw good light at low wattage in case you are on battery power alone.
Good luck!
You can ring the inside for good lighting with the white wall. I so far have them in my gun safe but not in the trailer..