Hi Owlsroost,
I have attached a picture of my favorite clamps in action.
The gray and green ones are from Menard's, the black and red I got at Sears, but not sure they still have them. They originally made by Wolfcraft. (I think)
You can reverse the heads on these and spread things as well as clamp which comes in very handy while holding things in place for a canoe.
I read a review somewhere saying they can apply more pressure than any other similar style clamp. They come in all sizes and you usually don't have enough.
I also use small "C" clamps and some of those "butterfly" type clamps.
I usually buy 2 to 4 clamps when they're on sale.
Good luck,
Paul