In 2009, I had a Thedford macerater mounted inside my bumper storage area. It was hardwired to the battery. Stinky slinky was gone and I was living large, with my poo pump and a 20 foot extendable hose which collapsed to a 7 foot, easily stored system. A notch in the upper angle bracket of the storage hold was necessary for the larger diameter of the end fitting. If you drill a hole through the back wall of the storage area to run your wire to the battery be sure you DO NOT DRILL A HOLE INTO YOUR GRAY WTER DRAIN LINE. (ahem)
Due to the shallowness of the bumper storage area, and the limited vertical distance from the 3" exit line of the trailer, this is not an optimum setup. It can be easily enhanced by raising the nose of the trailer before using the macerator, to allow for a better flow of "stuff" to the macerator. Run a small bit of gray water first, in order to "prime the pump", per se, and then close the gray, open the black, and, when it is complete, follow with the remaining gray.
My first pump lived for five years before going off to macerator heaven. The second one suffered an unforgivable abuse by its owner when a white plastic measuring spoon was flushed down the toilet with soapy dish water. ( I didn't see it, OK?)
After those two fails, I have returned to the ancient practice of gravity feed through a 3" stinky slinky. It has worked predictably since and I figure if gravity ever fails us, I have bigger problems to worry about. (Like spinning off the earth into space)