Had a funny thing happened on Saturday. I was telling the assembled stunned crowd how I observed every critter fleeing away as I approached with the whistles blowing. Someone said "Where have you got them?" and I said, "Well, they say not to mount them upside-down, but mine are under here..." to which I bent down to look under the headlight and saw only two white patches of double sided tape.
Hmmm. Maybe the tape was good enough by itself. Who needs Shoo Roos?
So yes, if you fit them, they're so strong they rip away from double-sided tape. Belt and braces with screws especially if you pay $30 for them.