If the rust spots are evenly spaced, you can use surface stitches to cover them. Good stitches might be Smyrna cross stitch, satin-stitch heart, queen stitch, satin stitch lozenges/triangles, palestrina knots, etc. If the spots are not evenly spaced, balance the design by adding extra stitches between the spots.
Fortunately, most states require drivers to equip their trailers with brakes and devices known as brake controllers. When a driver presses on the brake pedal in his truck, the brake controller lets the trailer's brake system know how much braking power is needed to stop the trailer.
A brake booster is an enhanced master cylinder setup used to reduce the amount of pedal pressure needed for braking. It employs a booster set up to act with the master cylinder to give higher hydraulic pressure to the brakes and/or lower force applied on the brake pedal through a brake booster push-rod.