Not only does this work, but it is also the only way to use a temple on a narrow project.
Because I don't have a lot of yarn, I weave quite narrow strips--3 to 5 inches usually. There are no temples available that are this narrow.
The images below show how to use some regular elastic and a couple of metal paper clamps. The trick is in the fastening. The fastening mechanism has to be kept out of the way of the beater. Once I had the elastics tied to the pole of a lamp on one side and a chair on the other. I've moved beyond that now with these two "quick clamps" available in most hardware stores. The other end of the elastic has a group of really big washers for weights that hang over the sides of the loom.
Just make sure you get the "pull" on each side as even as possible.