I have been doing this for years and have not found a good answer.
For me, I have hiked out of the Nitnat and other systems on the island back in the day with limits.
Over here, it is the Chehalis Canyon and a few other locations, and often 30-40 minute hikes, with a limit of 4 fish.
Many of the methods suggested are impractical if you are going to do this on a regular basis.
Doing a long hike with the added weight of a burlap sack is not fun.
I used to do this on the Fraser in the old days of the Sockeye and spring fishing fests.
Vest with a spring, two sockeye, a burlap sack in a garbage bag is heavy.
Also, no matter how hard you try and plan, you tend to get "damp" as well.
For me, I have one of the Mustang Inflatables in an XL, with the open back pouch.
This has been best for me.
I tend to use heavy duty Costco garbage bags.
Things I have found is for one, all teeth and pointy snouts will pierce garbage bags, thus vest stinks and I have come to accept that.
The bags get fine thin rips and leak as well.
A slimy vest which later drys with crispy stains and smells is the way it is for me.
One way to solve this is one of my buddies has found a tackle shop that sells heavy duty clear plastic bags in a tube shape (long and skinny) like a fish profile. These are expensive, but work well. I do not like them, for I think the bags can hold 2 fish each efficiently. Place two sets of two fish in bags, then try to place them in a vest leads to a lot of movement and the fish sliding out.
Another buddy has a specific tote bag made by Simms for the purpose of transporting expired fish.
I am not sure if it is rubber, rubber lined, or some kind of breathable material with a liner.
The tote is the grey colour of Simms waders. To describe it, it looks like a large sleeping bag storage bad, with back pack straps and a toggled draw string at the top so you can cinch it up. It is long and tall.
Of course it stinks like fish, but this is pretty much it's intended purpose.
Finally, one other buddy has the biggest looking polyester/nylon fishing vest I have ever seen.
I myself think it is ugly and do not like the feel of the material, but the fish pouch at the back dwarfs my cotton Mustang vest and it's pouch at the back.
Works well for him, and on occasion, he can spray it off/out with a hose, or put it in the washing machine as well.
Two worse experiences I have had to date was hauling out a limit of coho out of a canyon and ropes, with 2 of the fish being 12 lbs or so. Bag shifted lots and was not fun. Other one was hiking out of the NitNat with two springs, one being 55 lbs and the other being 52 lbs. The partner had a bad back and could not pack his fish. Finally gave up on the vest and had to put a dog leash through the gills and drag the fish on the leaves and moss. We quickly had two bears following us too close for comfort, and an aggressive black lab that felt the need to protect. I am still not sure if he helped or hindered the situation.
I also should add any method that involves you packing fish in some way using hand or hands as a way to hold the fish results in trouble. If you need to grab a hold of things to help balance you, I find hands are needed. also, walking on rocks, unstable ground, etc or what-not, it only takes one tumble, and your fish are down, and either dirty, bruised, you land on them, the possibilities are endless.
Dano