Since I didn't see anyone mentioning it I thought I would share another idea. I broke down last year and the only way out had some steep hills and whooped out trails with lots of sharp turns. No matter what we tried pulling it behind turboed long tracked sleds they would trench out and get stuck. We even tried 2 sleds tethered together with a good run.
Instead of towing we went to hauling. We thankfully had an older sled in the group to use for this experiment. With the bike on its side we put it on the sled's seat and tied the bike's skid and ski to the sled's running boards. I recommend taking the foot pegs off and putting something over the seat to protect it. The sled rider has to sit on the bike. The sled did great and tractored right up the hills. Getting the weight on the sleds track makes all the difference.
It also helped with the whoops and tight turns. Whoops tend to produce a lot of jerking on the tow strap and the tight turns cause off angle pulling on the tunnel.
We had to manipulate the sled and bike a couple of times to get through tight trees. Long side hills would be a problem since you can't get the sled on one ski. Short tippy sections can be handled by another rider holding down the end of the bike on the uphill side. There is a lot of leverage to take advantage of. For longer side hills I would consider going go back to towing.
The foot peg did tear the seat but the there was no other damage to the sled. Since you can bend a bumper or tunnel on a sled towing I think hauling may be a lower risk to the sled.
The tie down straps are already off in the picture but it gives the basic idea.
