I have the same brand 5er. It's not that hard, you don't need any extra pumps.
In side the water panel is a hook up to winterize your camper. Your unit should have come with a 5ft hose that has a conector on it. Screw that hose into the winterize spot on the panel. Make sure the pump is on,stick the hose in your water jug, turn the vavles till you hear water flowing in your tank. The pump will suck 5 gallons of water pretty quick.
If you need a longer hose Get a splice connector or make a longer one from scratch. I have filled my fresh tank this way a few times and it works great.
I don't rember what valves need to be turned but you can hear when the water is flowing, plus you water jug will empty quickly.
