On our Sunseeker, I access the plumbing through a port. Inside, a pick-up hose is rolled up and capped; I pull it through the port, and uncap it, then into a gallon of pink. Where the hose meets the valve, I turn the handle to point to the pick-up hose.
When the power to the pump is turned on, the pump pulls from the pick-up hose instead of pulling from the main tank.
This image is looking down into the area inside the port; the pick-up valve is on the right, tank/plumbing drain on the left:
I winterize as follows:
o Turn off pump.
o Rotate valves on water heater to winterize positions
o Park the MH on a slant to drain as much water as possible out of the tank.
o Vent pressure in WH by opening T&P valve momentarily, then drain water heater.
o Open tank drain; wait until it stops flowing.
o Open low water points just aft of the door: (apologies for the fuzzy image)
o Once all has drained, close the tank/plumbing drain valve.
o Turn on pump, then open all faucets for a few moments, then turn the pump off.
o Pull city water inlet screen, push on check valve to drain inlet line.
o Drive around a bit to further drain the lines.
o Park on an angle again so tank outlet is at low point.
o Close low points
o Turn off tank/plumbing drain.
o Pour pink gallon into tank.
o Run pump momentarily to winterize pipes to pump.
o Place winterizing pick-up hose in pink gallon, rotate valve to pick-up hose.
o Turn on pump.
o Open kitchen cold faucet which is the furthest away from pump, until a bit of pink arrives; close.
o Open hot faucet the furthest away from pump, until a bit of pink arrives; close.
o Open/close bathroom hot & cold faucets.
o Open/close shower faucets.
o Open toilet valve.
o Optionally, push city inlet check valve to get sprayed by pink...
o Turn off pump!
o Pour remainder of gallon in tank, if any.
o Turn winterizing valve to tank; store hose.
Two gallons is usually all it takes unless I screw up and pour a gallon on the ground because I forgot to cap the low water points.. Yes, I've done it more than once.
This post is way more info than the OP asked for, but I hope that helps!
2016 Forest River Sunseeker 2250SLEC Chevrolet 6.0L