"How the holy hell do you run on ammonia?"
Use it in a fuel cell.
In the 1960 Phillips built an electric bike running on Hydrazine, which is a cousin of Ammonia.
It's also toxic in WMD levels of exposure.
I'd agree a liquid fuel is the way to go. My ideal choice would be sugar soln in a fuel cell. Grow plant, chop up, add water, warm up a bit, filter then pour into tank.