I like the gear ratios.
Can you build a cheap, telescoping driveshaft that transmits 15-30HP despite large trailer articulation angles, trailer pitch, and body roll? It sounds complicated and problematic. You couldn't put it on the vehicle's centerline, because that's where the trailer coupler goes.
Mr. Sharkey reports that stability is not an issue with a VW Rabbit engine pushing a VW Rabbit EV, but he probably only operates at low speeds.
It's an interesting idea, but I can't picture how you'd make the driveshaft flexible enough. I think there are better alternatives.