They did it in 2014 as the final mountain stage of a 3 stage block after La Camperaona and Covadonga unipuertos and it was still choo choo until the final 5km, but I guess that was mostly dictated by the GC situation at the time.The problem with La Farrapona is never La Farrapona. It's that every single time they climb it they put Angliru the next day, so nobody ever wants to risk anything on San Lorenzo or do anything beyond the last 5km. Literally do those exact same stages the other way round and the chances of action on the Farrapona stage increase dramatically. Angliru is going to create gaps anyway, so you don't need to incentivise it by putting it on the last day before the rest day.
I just want to see Cobertoria and San Lorenzo without the big MTF that always neutralizes them.