I attempted the Velcro method on a
Surefire ST07 tape switch and found it severely lacking. It didn't hold well enough, was crooked, activation felt squishy with the Velcro underneath the switch, etc. I looked at various mounts on the market at the time but couldn't find anything that I liked AND would fit where I needed it to fit.
A Magpul soft ladder rail cover I had lying around was cut to the length of the tape switch. I traced out the outline of the switch, and hollowed out a cavity for the switch to rest in. This took a fair bit of trial, taking away a small amount of material before testing the fit and continuing. Once the switch fit I used super glue to hold it all together. This being a professional forum ghetto DIY methods aren't typically looked on with love and admiration, but it is at least as secure as the Velcro attachment that is considered acceptable. I've been using this set up for about two years now in snow, rain, temps ranging from 10 degrees to 100 degrees, without issue, including three or four training courses and two hunting seasons. Though this particular rifle isn't a work gun, I'd use it as one if I could. Even given a COTS tape switch rail mount, I don't believe I'd switch from this method as it is the lowest profile rail mounting method I've seen so far.
Unfortunately this won't be as low profile on your hand guard if you have to attach a rail section to make it happen, but if all else fails this is an option or a starting point to build on.