I know you said you didn't want permanent glue, but you may have to go that route. I ended up using marine epoxy on my velcro to keep it in place. I tried industrial strength and marine velcro, ruffing and smoothing the velcro area, and a few other glues. None of it worked. I figured if I ever want to get rid of it I'd scrape and sand a little bit. That worked as recently I removed some of the velcro (tendency for overkill) and had no problem removing it.

Hope this is helpful.