The reason the velcro fails is because the vapors from the plastic on the dash cause the adhesive to disintegrate. Something to do with polyvinyl Chloride, and the standard adhesive used on these products is vulnerable.
You might find some industrial double-faced tape that will work, but it may affect the dash plastic. Might as well drill the hole and be done with it.
I use a carpeted dash cover and simply slide the scan master under it. It holds the scanner in place ( as the wire is wedged in the seams of the dash) and it provides some cover from the glare. AND hides the scanner to a certain degree while protecting the delicate dash top plate all at the same time. No Velcro or adhesives go on the dash!