I use #10 propane tanks to burn weeds with a torch. #10 is lighter to carry around than a standard #20 tank.
I had the propane tank harness with the metal holder. After a few years the web straps all rotted away. Terrible. The metal is still fine, just no straps. I was going to buy another one on Amazon that had no metal. But the reviews said the straps can come apart at the stitching with no warning and are dangerous…tank can fall out.
I picked up an old scuba rig. Works great. Just need to wash it to get some of the mold off.
If you don’t want the weight of a steel propane tank on your back, (#10 = 13.3 pounds empty) you can get a #5 propane tank or a composite propane tank if you got some $$. (Study it up before you buy one. They have different regs)