Using hitch receivers is fairly common in welding shops. My son (the certified welder in the family) has several of them on his shop benches. For the truck, he uses the trailer towing hitch receiver at the back end of the truck to attach the vise, but he has a Z shaped piece that goes into the hitch receiver to raise the vise up to a more comfortable position. With two class 2 hitch receivers in this design, the vise isn't very stable at all, but it seems to work well enough for his needs.
When I want to use a vise, I like my vises to be very stationary and solid with no wobble, so I don't have these hitch receivers in my wood working shop. I have a small metal working vise that I mounted to a 3/4" plywood base, and the bottom of this base has a 1 1/2" square strip of red oak attached. When I need to use this metal working vise in my wood shop, I drop the oak part of this vise base into my woodworking bench vise and tighten the woodworking vise on it. it's very solid and stable, and the vise is only 3/4" higher than it would be if mounted directly to the bench. I have also used it with my Work-Mate portable benches in the same way. I much prefer this method over trying to use wobbly hitch receivers. A grinder or other semi portable power tool could also be mounted in a similar base and attached to your wood working bench this same way.
I also have a 18" X 36" piece of 3/4" birch plywood with a similar strip attached on the bottom that I use when I need a larger work surface on one of my Work-Mate benches. I originally made this table top for holding my former Delta lunchbox planer, but I now have a DeWalt 735 planer, and it's permanently mounted on a miter saw/planer stand. I now use this table top for many other uses, such as holding various wrenches, screwdrivers, and other hand tools near me, and at a convenient height, while working on one of my trucks, cars, or tractor.
Central North Carolina