I understand where you're coming from, but I feel like part of the challenge/fun is dealing with the pumpkin (or comparable biological alternatives) itself. I think for fairness sake, I'd have to say it wouldn't qualify.
While it wouldn't qualify for one of the listed prizes, I would encourage you to share your creation with us just for fun if you decide to go for it anyway! No promises, but Game Masters have been known to award fun little prizes for their personal favorites, including entries that are otherwise disqualified.
Pumpkin carving! :D
Question:
If we, er, aren't in a position to be able to work with actual vegetable matter, can we carve one of those synthetic, perma-pumpkins designed for carving on, as sold at craft stores?
(I won't have a place to/be allowed to work with a real pumpkin, but I'd love to have a chance to enter by carving a synthetic one!)