You only need one High level probe part on the craft oriented in any direction and another part that you can control from (ie: docking port junior, claw,cockpit, chair,QBE) pointing straight up. Control from that secondary point and SAS radial out when in 'surface mode' will try try to keep your craft straight and level.
I use this as my stock no mod auto pilot even on fixed wing craft. I like using docking ports so I have a attachment point if I want to lift things with a crane.