Y adapter for fresh water at park water supply post?

I attach water pressure regulator on CG faucet then a short hose.
On end of short hose I install a shutoff 'Y'---------one side is in-line water filter then potable water hose to city water connection/other side of 'Y' is a garden hose for general use------flushing of waste tanks/washing rv/hosing down etc.

Seeing as water tank flusher has a backflow preventor and 'y' is always pressurized not concerned with cross contamination