I am building one because it just makes sense to me.
1. i have a bad back and want to make riding as easy as possibe
2. wheel the sled out of the garage, hook up to winch and lift, won't tear up driveway.
3. tight parking spots
4. as i leaned this weekend, lifting a dead sled into a truck SUCKS.
5. no more dealing with blow outs, trailer lights and registering a trailer.
6. going to fast up a ramp and taking out your rear window.
7. some guys get better milage than towing.
8. weight over rear wheels = traction.
I am thinking of using a engine hoist for a crane/hoist. Cut the legs off add a winch, pulley and build a mounting base and there you go. Atleast i think it will work.
There's a few guy on here who have posted pics, search sled deck winch or crane. Hope this helps.