Our Born Free Class C was similarly designed to accommodate my wife's disabilities, including a box-mounted Thetford macerator & gate valves mounted at heights that she can reach.
We found a compartment on the driver's side rear, directly above the water heater and providing access to the drains & hot water bypass. That space is empty, and afforded us a place to store not only the supplied 21' coiled hose, but also an additional 21' extension hose.
(We also carry a 3' long standard sewer hose stored in its own tube, in case we need to bypass the macerator.)
One tip - many people store their sewer hoses in a plastic bin, to prevent any leakage within the storage compartment. Also, the Thetford sewer adapter has a cap on the drain side (1/2" - 3/4" garden hose connection).
The kneeler is a great idea; I work from a low-height folding chair, for the same purpose.
Good luck & keep traveling.
