Intermittent ... won't be intermittent for long if you don't find it.
And no pipes above that water could leak down from (ice machine, sink drain etc)?
1st Visual...(with hot water fired up) again with flash light real good and slow.
2nd paper towel (rats nest of hoses) maybe wrap a paper towel and hold in place with scotch tape. Leaker will be wet when leaks starts again.
3rd Do you have a way to test rv water regulator off from rv? I use a air compressor with its own regulator and a blow out plug. If regulator is bad it could be letting water in when city water pressure gets high. If you're at a place where water pressure is high during certain times of day.
If you have an air tester that keeps check valve open during testing, it would help separate if leak is from pressure side or discharge side. And most likely find the leak if leak is on high pressure side if you air up to around 45-55. Don't discount a water leak, leaking somewhere (prime suspect is hot water heater) and drip is flowing back, on outside of pipe.
