By chance I saw there is a regional airline in Portugal that connects small cities from North to South in a kind of "Portugal hopper"

https://en.wikipedia.org/wiki/Aero_VIP_(Portugal)
http://bookings.aerovip.pt

They fly Braganca - Vila Real - Viseu - Cascais - Portimao once a day (two in summer) except Sundays. Prices are not exactly Ryanair but they are kind of well priced for this type of shuttle service. You can buy Braganca - Portimao in the same ticket.

They fly with a Dornier Do 228 which I had never had the chance to fly.

Braganca is not far from Zamora in Spain which is easily accesible with high-speed train from Madrid (1h30') and which is a Romanesque town I would like to visit. Portimao is a major tourist destination itself not far from Faro. So while not your evident airports, I think they are "reachable" with a bit of logistics at play.

So I was wondering if some air freak has flown this. I am tempted! 4 segments, 5 new airports, 1 new aircraft type and 1 new airline... not bad

Any feedback welcomed.

Yes, I did. Well, part of the route.

Cascais - Viseu - Vila Real in November.

Vila Real is 90' from Porto by bus. Cascais is next to Lisbon.