I’ve got some really strong Velcro that I use to use for mounting signs with. It needs my little Morrison’s key fob card to slide in-between to take them off & stick them inside my kit bag for storage. Also means I can charge them easily too
(I can’t recall the 3M series number but a good sign writers would likely have the strong stuff & easily as good as dual lock)
I’ve seen someone using rubber bands successfully too.