I'd use a stamp if we had one, wanted to redo my signature anyway. Then adding on to the prizes as stat gain or loss for everyone who entered, like if your horses didn't do well or if it did well you would lose or gain accordingly. As for as actual prizes, maybe special or different tack or just tack, in general, I've seen given out at horse shows before. Could have special stats or something that give a boost to your horse, could have it where this couldn't be sold if you wanted to keep it limited.
Working
Username: Yellow.
Bank Link: here
Stable Link: Running Rivers Stable
I’d like to train my horse!
Horse’s name: Blaze
Horse breed: Aquell Warmblood
Main Training Focus (speed, stamina, etc): Speed
Link: here
I’d like to train my horse!
Horse’s name: Midnight
Horse breed: Boh Tot
Main Training Focus (speed, stamina, etc): Speed
Link: here
I’d like to train my horse!
Horse’s name: Annekal
Horse breed: Dyselde Draft
Main Training Focus (speed, stamina, etc): Agility
Link: here