I've had one of those cargo carriers for about 10 years. I think I've used it twice. I honestly didn't like it.
A couple things I've found. These may or may not apply to putting on a snowcat.
- Vehicles with a flat back has a low-pressure area directly behind the vehicle that sucks in whatever is airborne (mist, snow, dust...). Well, all that dumps on whatever is in your carrier. I got around this by getting a huge duffle bag that's made for these things and putting my contents in there and zippering it up. BTW, although I never use the carrier anymore, the bag is handy when I put luggage in the back of the pickup. It keeps the weather off the suitcases.
- They're kind of a PITA to put on, take off and store. Probably not an issue for your snowcat but if you take one on vacation, you need to carry it up to your hotel room or store someplace. If you leave it on, it's hard to see when parking and is also a shin buster. They do have flip-up ones now that would address that issue (but you need to fold it back down to open the rear hatch/tailgate of the vehicle).
- I don't recall the exact details since it's been several years since I've used it but the slop between the drawbar and receiver allows the carrier to dip on the ends and rattle some. As I recall, overloading to one side to bind it a bit helped (put a heavy cooler on one side and sleeping bags on the other).