Sounds like a jet ski is a lot like a sled. I find sled engines to be fascinating, and they are a lot like jet ski engines. Tons more power than I ever thought they would have. Most sled and ski engines put the majority of motorcycles to shame, and I love motorcycles. I didn't know sled trails were different, but I haven't gotten into off roading stuff around here yet. If you want to ride an ATV in the south it's mostly done on private land, not a lot of state maintained trails. I used to frequent a few ATV parks that were privately owned and then hit the Uwharrie national forest, but those trails are shared with Jeeps and stuff like that, which I also like. I'd like to get a Honda Pioneer or a Ural Gear Up and ride the sunrise trail, but that will have to wait until the house is fixed I think.
While some sleds are still two-strokers, most manufacturers also sell four strokes. One of the first to do so was Yamaha which took the 998 cc engine out of their R1 motorcycle and dropped it into the RX-1 with a few tweaks. While heavy, that early sled could certainly move . . .
Honestly, the largest sled I have is a 598 cc two-stroke which is fine for my type of trails and riding style (although I may step up to either a 900 cc or 1200 cc four stroke for my next sled so I don't have to continue to buy two stroke oil.)
Here in Maine some trails are shared ATV and snowmobile (although not at the same time unless the ATV has tracks and is registered as a sled) . . . and the vast majority are on privately owned land with a few exceptions.
Incidentally, the Sunrise Trail is OK . . . but there are many better trails to ride that are not long, straight, no turn, former railroad beds.