The Kawasaki Mules I think may be better suited to more yard/sooth terrain bush work/utility work. I have done some reading on the Yamaha Rhino, and they seem like they would be a better mix of true All terrain/Utility/Work/Play
The Rhino has almost ATV manuverability and ground clearance, can still haul a pretty good load as well and would still be a blast for pure play....
A regular 4 wheeler can be very handy as well. I have a Honda 450ES 4x4 and it can pull a pretty decent load. My 1 utility trailer is approx 5x8 with 2ft sides, my quad pulls it pretty easily with the trailer full of firewood with a nice rounded heap to it, even down the road at 35 MPH, I don't like doing that much though, too much weight behind if I ever had to try to stop fast I'm sure the trailer would try to keep on going........ For little garden tractor trailers, Mine is one of the larger 17 CuFt models, and I can heap that up and not even know it's there....
Here's a pic of my ATV
As far as dragging logs, a logging arch would be the cat's meow.... Dragging logs behind does not work very good if they can dig in etc... I have heard peaple recommend putting the butt of the log on an old car hood which would probably work quite well... Last winter/spring a friend's uncle got a contract to do some road clearing for a new subdivision, he cut and skid out the wood he wanted and burnt the brush. he gave us permission to take what we wanted of the left over wood, lots were logs which must have been forgotten under the snow when he was there because most was anywhere from approx 12-18" in diameter and lots of them were anywhere from 10-16 feet long. Between my buddy and I we ended up with 15 or 16 FULL pickup loads full of firewood to split... We skidded all logs anywhere from 1/4 to 1/2 mile or so to the trucks then blocked and loaded it there using my atv, the "skidder trail" even went through a couple really soft/wet areas, but the atv did a pretty good job thanks to my aggressive tires.... Once we had a log ready to skid, we would prop the butt end of it up off the ground some, then back the bike up to it, using a heavy 2" rachet strap i'd attach one end to one of the rear rack supports, then sling the other end to the other rear rack support. using another 2" rachet strap I would double it around the log and "rack sling" then back to itself... then I'd rachet up the 'rack sling rachet strap' to make sure the butt of the log was up and off the ground and then it was good to go....
With some of the larger logs the front end got a little light, and when turning I would have to stand up and lean forward some, but it did a good job skidding.... I wish I had taken some pics...