I don't know if the Tonneau cover itself would need to incorporate a high level brake light, the hardtop has one, the soft top has two, if neither of those is fitted do you need an alternative arangement?
That blue car with the hardtop is £90k Aeros are going to be looking like the cheap option soon if the prices keep going up like this.
I don't know about the extra brake light, I do know you can get a 2020 Plus Six with 800 miles on it for 80k so a bit of a no brainer really and as you suggest the Aero's will come into their own and the new 3 wheeler if they have got it right this time and around the 60k point..