Most bag companies have been mentioned. I have both Warhorse and Wiebad. Both serve their purpose. I attach my Warhorse Clede using an arca plate (manufacturer my son from a cutting board) to my KRG chassis's arca rail - easy on easy off. I have a light weight and a heavy weight CledeX. See website for materials. They work very well on rails, posts/tripod without clamp or time to clamp, wide slots like a cattle gate. The light one helps when lots of movement. The heavy one extra long range like 400 & 500 yards 22LR on a roof - where peak rest is allowed.....etc
I have 2 wiebad bags a fortune cookie (FC) and a Whiskey Charlie (WC) mini wax canvas bags. Each has their purpose. The larger fortune cookie with extended bipod and rear FC bag for prone with high grass blocking when low prone, for example. The FC is larger than and has non-slip on under curved side and is waxed canvas. The WC that I selected - chose (choice of color but only sand in stock) was waxed canvas and curved under belly slick, smaller and light weight. This worked well on inside of tire on the rim and on top, as well thru woven wire fence, and between windshield and car door jam. WC is Smaller and lighter bag.
Your best bet is to go to a PRS or NRL or MARS match and see if you can touchy freely or get opinions.
The top shooters, which I am not, just old and full of it, say buy one bag and use only one bag and practice with all positions & different barricades and stuff.
P.S.
Oh, by the way, a cheap way is a pair of sweat or tube socks filled with USED air soft pellets. (Not affected by water, humidity and are slick) Fill one sock, not too full, tie it securely and put the knot first inside the other sock and tie it securely.
Guys, this is the closest thing to what I'm looking for (Solo Sack). Watch the second bag she demos in her video. It, for the most part, does what I had in mind. The price ain't bad either...