I'm with the first reply. Once I figured out how to bone out an animal and butcher it in the field, I've never carried out bone again. With practice, you'll get better. I can take my time and do an elk in 3 hours by myself. In a pinch, on a hot day, with 2 elk down and 2 of us, I did both elk in that time. I carry a Gerber Bolt Action Exchange blade knife and a folding filet knife. I don't use a saw anymore. I bag mine in clear plastic bags, and hide the meat away from the gut pile a couple of hundred yards. That has worked so far. I keep an extra sleeping bag, food, etc. at the truck so I can stay there overnight, if it is too late to get back to my backpack camp.
My buddy uses a GoLite Jam. It is rated for 30 lbs, and will handle more if you're careful. No need for a frame if you bone the animal. When he gets to the truck, he changes to a heavier pack. I use a slightly heavier pack that weighs 3-1/2 lbs. after I cut off all of the non-essential crap that they put on to fool the newbies. I use a Kelty now, and it ripped the first time I loaded it over 80 lbs. , I can pack out a cow in 3 loads usually. If the hike is tough, I pack lighter. I can go over anything with a 50 lb. pack. I've used the cheap camo packs from Walmart with good success. I bought the Kelty thinking it would hold up better, but it didn't. I carry a mini waterpump plier (about 5" long), dental floss, and a leather needle (about 3/64" thick) to sew up boots and packs. I've used it more than once. I even sewed a saddle once, but I had to heat up the needle to pre-drill the holes through the leather. I ripped my pack with a 100 lbs. of deer before I knew how to bone them out. The sewing kit worked.
The big thing is to be in shape. The best way I've found is to load your pack with 45 lbs. of sand or lead, and walk 3 miles a few times a week. You'll get used to the pain of the pack straps, and build uphill muscles you don't build by biking, running, or just walking. The Forest Service Fire Fighters walk 3 miles in 45 minutes with 45 lbs. in order to qualify to work fire. It works even on flat ground. I'm 60 now, and I go slower, but I still carry 45 or 50 lbs. to get in shape.
Once you know you can pack out an animal, you can't hunt where others can't. Good luck.