Ok then. Blood and Wine definitely adds more overall content to the game and does an excellent job of capping off the series, but I think Heart of Stone is the better story of the two.
Another option always on the table is to use the same Handwavium™ that runs the STUN suits, if you don't want to deal with the constraints of modern day technology.
If I were to build something from the ground up and wanted to forge my own way instead of, say, a kit helicopter, I'd likely do a gas engine tri-copter. Something with enough shaft horsepower to spin some larger and more efficient blades.
But seriously, the explosion risk from hydrogen fuel cells, gas engines, or lithium batteries is about the same across the board when you discount human factors
The most popular line of research is towards hydrogen fuel cells, although if you're open to more banal alternatives, jet fuel still has fantastic power density.
Until I played one of the Carmen games from 1995 with Lynn Thigpen, and I found a note left behind from one of her agents, I didn't realize that Carmen pays her people too Lol