If you have time, would like to see some pictures of your fix (if possible). I occasionally have the same problem. I bought the repair kit for the Shurflo, and bought a check valve and connectors, but decided to replace the city water inlet because it also has a check valve. Everything was fine on my last trip, but too early to tell.
2013 Itasca Sunstar 26HE
Firestone Airbags, Hellwig front/rear Anti-Sway Bars,
Rear Trac Bar, Safe-T-Plus, and 480 watt solar system.