Point of clarification--are you referring to buying a ticket and having someone else pick up your bag (and therefore your pony) for you? Because if that's the case, I don't think that will be possible, without con staff permission. Normally someone picking up a loot bag has to have ID to prove they're the person who's bag they're picking up. It's to keep someone from stealing someone else's badge/bag; I'm sure you can guess why
that became SOP at conventions (the few always ruin things for everyone else *sigh*).
I would contact fair staff and see what can be done, before you buy a ticket. I know they allowed some people to buy the llama pony at the main fair, but they didn't have many extra to sell, so they did a kind of raffle-type drawing to select the people who could buy one. They may have more after PFW--pretty sure they were being careful to make sure they had enough for the upcoming convention.
I hope you're able to work something out. Good luck!