Fresh water fill ports on 1999 Holiday Rambler ?'s

I purchased a very well kept 1999 Holiday Rambler Alum-lite travel trailer and have some questions about the way to get water into the holding tank. This is the 5th RV I have owned and the first wit5h this type of set up. In the compartment where the handles to empty the tanks are located there are 3 valves that you could hook a hose to. The valve on the right is the black water cleanout as it is labeled. I am thinking the center valve is for hooking to a city water supply because it has the pressure valve and the one on the left is for filling the fresh water tank from a remote water tote. I use this in a remote location and have always filled the others via gravity port located somewhere on the trailer, but this trailer does not have a gravity fill port. I am guessing on this one that I will need a water transfer pump to get the water from the holding tank in the back of my pickup to the valve via hose and the water transfer pump. Do you think this is correct and if so, what size pump as far a HP would I need to get?
I would appreciate any help or suggestions. Not sure how to post pics or I would post pics of this set up on my RV.
Thanks