For those of you who decide to bolt the snap-up in, here's something to watch out for:

That's a photo of a stud in the top hole of a Reese heavy duty snap-up. The top chain link in the photo is on the hook of the snap-up. The chain is hitting the stud. I'm pretty sure it pushes out the chain far enough to defeat the "locking" action of the snap-up. I ended up ditching the washer, cutting the stud flush to the nut and then grinding down the nut/stud even more to gain the proper clearance.
In most cases people would be using a bolt here and I suspect the clearance for a bolt head would be fine. However, it's still worth checking, especially if there's a washer used under the bolt head.
I must have installed this 10 times before noticing the chain hitting.