Farrier school ?
You have a rig and trailer, howabout gettign a CDL some insurance and horse hauling ?
You could go the smoke and mirrors rout, change your name to moonbeam dancer and get into the hocus pocus horse healing,
Endurance rider horse consulting ?
Oohh ooh I know I know, all horsey eventually die, gotta do something with em.. Horsy mortician ?