It's not that hard if you can handle some basic plumbing and 12V wiring. Here's a diagram of how our 1993 13' Scamp is plumbed with both a hand pump and electric pump. The hand pump has to be in good working order and have a check valve inside it preventing backflow so the system holds prime.
Thanks for all the responses. Wilder, I like the idea of using the city faucet as you've diagrammed, in part because it appears the hand pump could still be used if necessary. Would I need a second check valve somewhere in the system? Now, to truly reveal my ignorance, I have to ask whether the system you've described requires a switch to turn the pump on, or if it comes on automatically when you open the faucet.
P.S. Okay, I see you've already said a second check valve is required; I assume that goes just under the hand pump?