Some confusion and questions Dave.
Is it you in the video?
And who are "we"???
Not mentioned....
You say "My favorite is 1700 cm2 and AR > 7", but for which conditions and sport?
As it looks like flat water pumping in the video, but for wingfoil and especially kitefoil 1700 cm2 and this AR is pretty useless for most.
And a 75 cm mast is super short for kitefoil and wingfoil, so assume you mean for "pump" foil or surffoil?
A bit confusing to bring it all together like this, sorry to say.
I know you have good intentions, as to advice everyone totally new to foiling, I love that - but IMO you need to be more precise and differentiate between the totally different disciplines, requiring very different foils.
Peter