I use the same full size hitch hauler as I use on my truck. There is a smaller version for ATVs if that is what you are refering to. I have not had any problem with the hauler being too small. Yes, the deer does hang off but I always have parachute cord with me to tie up the legs and head. I tie them to the back rack to keep them up higher. I guess it also serves to get some of the weight off the hitch.

As for the 150 lb weight limit, I would just weld a few supports on each side of the bar. Make them long enough to reach each of the three sections and weld diagonally. That should beef up the weak link (factory weld angles) and allow even a larger deer to be carried. Of course, one problem with some ATVs may be all that weight out back making the front end light.

As I said, I have the angled tube and not the straight tube mount. The straight tube does not allow enough ground clearance as mentioned by others when on uneven terrain.

Hitch hauler clearance bar

 

I have not seen this hitch hauler but what would happen if you relocated the mount to the platform and moved it over the rear rack, then an extension could be built to extend it back out behind the ATV. This would move some wt foreward and the extension could be removeable so it wouldn't get caught on rougher terrain when not in use. Just a thought?

 

Go look at this guys. BPS has it on sale for like 60$. Plus you can use it on your truck. I also believe that this sucker will hold more than 150 lbs. Im thinking atlease 300.