All understood. Actually, what I said in #2 is that TT does not recommend their own vent mount for these heavier devices, and that it comes as no surprise.
Thought it would be worth a look, but in neither of our cases did Brodit recommend a vent mount. They do sell them, but they must be for vehicles with vents with super heavy plastic that don't flap around easily.
I suspect the OP would also be better off with one of the clip sort they recommend for my vehicle and yours.