Hey mate, Ive VHB taped my Renogy 100W flexi solar panel to my RTT ~12months ago and have had zero problems.
Ive used in camping situations during summer around the 38deg C to in winter around the -8deg C, and whilst I read posts of people stating there will be output loss, and extreme heat, and it wont work, and sky is falling, blah blah blah - all due to it being mounted directly to the roof of the RTT, I cant say I have 1) noticed enough to care about it and 2) the BMS is more than happy with the constant feed of solar to manage the 2nd battery each day.
The tape was purchsed on Amazon
3M Scotch 5952 VHB Tape and one roll did the job within about an inch of spare tape.