What I do is to mount the strut to the wing with a hinge - either a hinge point or a flat nylon pinned hinge screwed to the underside of the wing.

Then I put a dowel on two ends of a rubber band. Slip the dowel between the struts, pull the rubber band under the fuse and secure it to the other strut.

The rubber will hold the struts in place, and once you remove it, the struts will lay flat against the bottom of the wing.