Yeah a Shot and drop would be theoretically perfect. (If only the council would change the planning rules, maybe that's AT why that have given up on Flats as it's to hard to have small footprint but large and intense rides).a shot 'n' drop tower (like Ice Blast at BPB and Cliffhanger at FL) would fit that criteria -, they don't take long to load/unload, have a short ride cycle and pack a punch- but AT wouldn't be able to get one unless it was partly in a hole in the ground, due to the height restrictions (hence why Nemesis was built in a pit).
Sticking with the pit theme they could have it where you start of in the pit (underground bunker maybe ?)and the ground shaking as the Nemesis creature moves is enough to propel you from the underground pit into the sky. But the digging pit defeats the idea of the flat ride being a cheap and easy addition to the park.