Steve's way probably would work best unless the ability to rotate the glider so it's angled instead of straight upside down is really needed. With a few friends it's not difficult to invert the fuselage and support it on padded sawhorses with the canopy off. If the top of the vertical fin has a reasonably large and strong attachment point for a T-tail you can use it to support the aft end of the fuse. On my ASW-15 I needed to make a high saddle to sit the rear of the tailboom in because the rudder extends above the top of the fin but a simple 2x4 A-frame with a canvas strap on top to make a support saddle took care of that.