Scot: The situation you describe is a new one for me-- taking the carcass into the processor without gutting.
I had to do it once. It's a long story as to why, but I arrived at the processor well after dark and the fellow was nice enough to hold the flashlight for me while I did what needed to be done in the parking lot.
JPH: I actually have seen gut piles last. In fact, I've seen them rot into the ground. It's a rarity to be sure. I normally place them in a spot out in the field where I can watch what comes to it with binos, and sometimes a rifle scope. They're usually gone within 2 hours-- some in as little as 20 minutes. However, a few have lasted, and I can't say why with certainty. There have been two. They both got put out at night during the height of season. They both were put out in a year where I had heard the rumor that parvo had put a serious hurt on the coyotes. However, that would not explain why the buzzards didn't hit them the next morning. The only other odd thing about these instances was that I had to place the piles a bit closer to the house in a different spot. The fields were exceptionally wet that year, and I had to dump them wherever I could get solid traction.