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.
brake system, brakes - a braking device consisting of a combination of interacting parts that work to slow a motor vehicle. disc brake, disk brake - hydraulic brake in which friction is applied to both sides of a spinning disk by the brake pads. drum brake - hydraulic brake in which friction is applied to the inside of a spinning drum by the brake shoe. foot brake - hydraulic brake operated by pressing on a foot pedal.