And don't get all carried away when putting that template on, it does not have to be firmly pressed down everywhere. Just light pressure, just enough to of course allow for accurate placement of the vg's, and so that it follows the string line, but the entire template does not have to be stuck down tight everywhere else. NOT sticking it all down firmly really helps in it's removal. And yeah, get it off ASAP.
As to their glue, I used some 8 year old opened glue to stick down a few VG's on the rear of my hatchback car, kind of a worse case to see how good that glue is. A year later they are all still there, as are all the ones on the plane, good glue!