An alternative might be a panorama head and a telephoto lens. The additional resolution may help out enough, though processing will take up even more time and work. Panoramic heads are great for interior shots too, IMHO. I use it all the time.
Another alternative... a _really_ tall tripod, if that exists. Say you can get it up to 2 meters, maybe more. Perhaps hold it up (or a monopod). Then a K-S2, with WiFi so you have some control over the shot (can see what the camera sees on your phone), though when you hold it up you'd need someone to assist you. Or park your car in front of the building and climb onto the car.
You can still use composition adjustment (which the K-S2 probably has?) to get even further in any case. The K-S2 also has the advantage of a flippy screen over the K-3, so you can shoot from a higher position compared to having to use the OVF or a fixed LCD screen.
Basically, try to think of a way to shoot from as high a position as possible. And feel free to combine several things to get it done... wider lens + composition adjustment + higher shooting position. Good luck!