I was reading up on this, seeing how I have to finish the skirts on my table, and someone was suggesting This: "Forget the clamps, here is the deal. Rip the edges at 45°, pass it on the jointer, lay the two parts face up on a table with the edges touching. Lay a piece of 2" masking tape down the seam, turn it over, squirt some glue in the joint, then fold it closed. Let it dry. You will never do it any other way." (Sorry I don't know the source's name, it wasn't posted where I found the information)
I was thinking, damn, that's a pretty ingenous way to do it. Keeps the outside corners together and the weight of the wood will keep the inside corners touching. I'll have to give it a try tonight, see if it passes muster.