I need a horse....and quick!

Mark told me his plan today...the plan to find out if Santa is real or not. He's going to write a letter to him and ask him to leave a reindeer footprint on Christmas Eve. I told him that was a great idea...but, there is no snow. He figures he will leave an inkpad out and he said "You don't have a horse, so I know that if there is a footprint, then it's really one of Santa's reindeers"

So, I guess I need to come up with a plan of my own. Should I take a piece of paper to the Animal Farm and have Farmer Tim make me a footprint. Or should I write a letter back to Mark, as Santa, and explain that there is no time to collect footprints on Christmas Eve. Or maybe that the reindeer were to stubborn to cooperate, but that I (Santa) tried my best.