Marksmanship is the critical component. That is simply good and true advice. But if you are shooting at LR or XLR the human body is simply not stable enough. I can shoot standing or sitting further than most, and I play PRS and tactical steel matches, so improvised shooting positions are the name of the game. That said, a good tripod (mine is 40lb capacity) with legs that will splay and a Hog Saddle (or Pig Saddle) is about the only way to get near bench stability just about anywhere.
Shooting sticks and monopods can be helpful, which is why they’re so prevalent in big game hunting, but reaching out to doped distances where you’re dialing big numbers they’re not stable enough to take ethical shots (or hit fractions of a minute targets) which is why those shots are not typically done.
Again, that is not to say I don’t completely agree with all the posts about improving ones marksmanship first and foremost, but I compete with some truly amazing shooters who use everything and anything to gain the advantage of more stability, and the OP has a point that often in the real world you can’t get low. The closer to the earth you are the better the position. There is a reason lots of TS and PRS matches don’t allow tripods and saddles. It’s because on many stages they offer huge advantage.
Rigging tripods for shooting has been around in the the sniper and swat communities for many years. With light but strong carbon fiber models like those made by Manfrotto and Slick they’ve become more practical to carry in the field. A good rig can cost upwards of $800, which is a new rifle, so you sort of have to really have a need.
This is what you’re asking for though. I use mine in competition, but two years ago I used it in a ground blind in Kansas and shot a deer at a great distance. Without it I would not have taken the shot. I think it’s a waste of money unless you compete seriously or you are a professional, but that’s the only truly portable rest I know of that will get you close to the stability of shooting off a rest on a range. It’s no Sinclaire bench rest, but it’s way, way, way more stable than anything that’s been discussed.