Not much to add but I recently had a similar problem. Pull the lights on and the fuel gauge would drop to empty and then the truck would die. I’m thinking ground but haven’t tracked it down yet.
I’ve read that the front drive shaft can have some clearance issues on factory height trucks. I have no personal experience with this though.
I’m anxious to see how this works out. I’m also interested in that extra gear.
Not much help, but I just bolted mine to the frame rail and reconnected the wiring. I bypassed it with the plumbing but the tank selector has to be set to the right tank. Not ideal but it works and I can move the tank selector switch to the opposite tank for theft protection.