City Water Intake and Quick Connects- dust cap?

I apologize, everyone, for not responding to all your great suggestions. We are replacing our EPDM roof and have to get it done before our next trip on the 22nd (and the TT is parked outside, so weather and daylight are factors). Weather permitting and God willing, we'll get that wrapped up soon and then I can focus again on these smaller (but no less aggravating) matters. I'll post a picture of the solution I find. Y'all have given me some great resources to explore-- thank you!
Stay tuned...