After hauling bikes for many years I still say a solid block under frame is the only way. My wing takes s 24" 2 x 6, 4 2 x 4 x 24" and a 1 x 4. Lift up the rear end (by hand) slip it under the frame and lash it down. Don't have to compress shock's just snug it. Haven't lost one since I started using that method.
2005 Wolf Pack WP22-2016 Grey Wolf 26RR-Gone
2004 Siverado 2500HD Duramax
2013 Keystone Springdale 5r
1998 Honda Valkerie
2016 Camping 148 days so far