Pretty sure you could just make a custom button that can be rendered according to permission set instead. 

I do think your suggestion is more polished though!

We did something like that in this post but it got too complicated.

Is that what you had in mind?

Or did you mean have the button perform a custom export function? The problem is, the export function on the model object doesn’t get capture UI only fields and templates.

Oh good point. 

Yeah I see now. I never have tried this myself but it made logical sense. 
Would be a great feature!