In the case of what U-Haul set my nephew up with, it violated factors one and two big time. Loading the car forward with more tongue weight was the best we could do, but it does not make up for the geometry problem.
That was the closest I've ever been to a wreck from the oscillation that developed. U-haul should not have rented such a set up...but did. I'll bet the hitch was about 6-7 feet from the axle and it was a short wheel base truck/van (with duels at least). Mobile home haulers are real close, yes.
Re electrical, isn't a resistor placed in series that is equal to the resistance (of all of the lights) going to give you half of the 24v (12v) going through the trailer lights? These are brake lights I believe, otherwise I would just go from one battery for 12vdc.