I had this idea yesterday and gave it a try and it works, just not as well or easily as I had hoped. I was looking for a way to extend the reach of pipe clamp jaws. Pipe clamps are great for spanning long distances, I've had mine out to 12' once, but the 2" wide jaw sometimes leaves a bit to be desired. So I laminated 3 pieces of plywood together x 2 and drilled holes in them the size of my pipes (I had to file them to the right size, I didn't have a bit exactly the right size). I was hoping that by keeping the holes tight around the pipes that I could keep from skewing the extra jaws apart but that didn't work out. So I tried adding a bridge between the extended jaws that was the same thickness as what I was clamping. This is shown in the photo. That worked. To go out much longer a 2 x 4 could be used as a bridge.
It clamped very tightly but it is awkward to use, for anything long it would take 2 people to do it but it is an option where a long reach is needed.