Fishy, I'm trying to make a frame/cage in the trunk where I can just slide in the amps. Makes it easier for replacing amps and wires. I have a set for winter and summer. Right now I have to unscrew and screw. So far the only way it'll happen screwless is to mount a frame on the bottom of the amp and then slide it into the cage. Then have some kind of locking system to hold it in place.
I have 2 amps held down by velcro, but its the double lock kind. It's 5 times stronger than the regular fuzz against loop kind. I have a textured black painted box with 4 subs, and on each side of the subs are 2 stainless steel plates. The amps are velcroed down on to the plates. For 2 and a half years now they have not budged. The double lock kind, you get no play like you do the other kind.