That handle hauler Is Ok but I made mine out of an old piece of seat belt material so I could put It over my shoulder. A lot easier to do It that way then hauling with one hand. Then both your hands are free and you can use your walking stick to It's full advantage.
You can also use a back pack frame. And just ratchet strap the beaver to the pack frame. It's also a easy way to pack In traps.
The other thing I always did was to gut my beaver before hauling them out. It's a easy way to lose about 10 lbs.
Pack frame works good, I always like the old army ones for packing quarters of meat out, or multiple beaver at a time. If you don't have one of those or you don't plan on packing out more than a beaver or two at a time start checking out the thrift stores. You can find external frame packs for around $5, you want the old style flap top style where it is all one big compartment. Just drop the beaver in from the top and throw it on your back. Fast, easy and no strapping down involved, also a great way to pack traps in. Warning; you put three or four decent size beaver in one though and you can have problems. I broke a couple of the aluminum frames right in half trying to pack too many beaver at once out with them. I would 75-80 pounds max on them, maybe a hundred if you aren't having to crawl over logs or other obstacles. I know with 120-150 pounds in them I would go to sling my leg over a log, the beavers in the packsack would flop from one side to the other and try and fling me to the ground, and if that was unsuccessful they would strain the aluminum tube frame and eventually it would break.
I tried gutting a bunch of beaver once. For my money after skinning a dozen floppy, gutless beaver; I'll rough skin them if I'm trying to lose weight that bad.