If you are having problems getting water to flow downhill out of a hose, then surely you do not have the background to prevent problems like backflow or a cross-connection. You could accidentally make someone very sick.
Think it over.
====== Plan B. YOU stay in the trailer and let the guests stay in the house. When you need to go #1, find a bush. When you need to go #2, go to the house. Drink bottled water.