Think outside the box....
I used to use a heavy leather bag with 2 pockets I picked up at Lowe's. Lesche in the sheath that it came with and the same with the GPP.
Last year we picked up some of these to use as prizes for a seeded hunt and I purchased one for myself.
This is a Browning Trapper Creek Half Vest. The quick clip around belt is built into it and can adjust for a large guy. Both of the sides on the front have TWO nice, deep pockets each. The pockets have snaps to extend to larger sizes. The back is mesh and has openings with elastic at an angle at the top of both sides. The bottom of the mesh has a zip for ease of emptying it. It was designed for going hunting / target shooting with shotguns. This half vest even has built-in side D rings.
Is it super heavy, rugged material? No. But it's handy and LIGHTWEIGHT. I don't miss that heavy leather bag trying to drag my pants down. Besides, now I have a bit of cover in the back if they slip. lol No mooning people while digging!
It's nice having the belt built in. A few members throw a bottle of water into the part hanging at back. If you had trash that wasn't SHARP, you could dump it back there easily by feel and then just unzip to dump it after the hunt. Jagged edges would be bad on the mesh. If you or the Mrs. were handy with a sewing machine, you could mod one of these quite a few ways to suit your needs (extra little pocket / loop for the propointer inside a pocket, etc).
They retailed for $40 but we got them from an overstock site for around $17 and change ea. I'm not saying this is a solution for you, necessarily, but I can't tell you how much I enjoy using this lightweight solution over that heavy bag when out swinging the machine. Think outside the normal solutions everyone uses...
I'd eliminate the kneeling pad with a good pair of knee pads.