I love the clever use of connectors. I wound up using jumper cables and a "poop battery" whose sole job was to provide the 20 amps for the pump, and was kept trickle charged.
I would highly recommend the FloJet. A few items I found:
1: Get a stool or portable chair to sit on. kneeling to attach and man the pump is not fun for the back.
2: Get a transparent sleeve between the sewage port and the macerator pump. You want to shut off the macerator pump just as it empties, because it will burn out and destroy itself if run dry for more than a few seconds.
3: With the pump in place, you can empty the black tank, then open both valves, allow the gray tank to backflush the black, then empty that... saves a lot of water, and does the same job for clog prevention.
4: I personally use a black rubber hose with words on it plainly marked, "NOT FOR POTABLE WATER". The hose I use to flush out the macerator pump is green, and has vacuum breaker check valves on both ends. My white fresh water hoses are stashed in a separate compartment.
5: I used an extra-wide hose, especially when going distances of 50 to 100 feet.
6: The pump gets stored in its own plastic tub with a tight-fitting lid, and it, as well as the hoses get capped after use.
7: This isn't the OP's use, but if using a "blue boy" waste tank with a pickup truck, place it in the truck bed while it is empty, use the macerator pump to fill it up, drive to the dump station, hook up a slinky, and let gravity do the work. This is a lot easier than trying to heave a full tank into the truck bed.