I have a 2014 31SL. What should I set the water pressure to? I have been setting to 40 psi but some other campers told me a min of 60 should be reasonable.

I run ours at 55 for 4 years fulltime and worked fine made a difference from 40

The regulator I bought was preset at 55 psi & provided the park has that much or more it's a good pressure, but the majority of places we've stayed had less at the faucet, seems 40-45 is about park average.

I have my Watts set at 60 with no issues

I have my Watts set at 60 with no issues

Mine was also a Watts regulator.

From what I've been told, RIVA requires testing the fresh water system at 85 psi, and recommends testing at 100 psi. Technically, if your RV has a RIVA sticker, it should have been tested at 85 psi on up to 100 psi. One can take that for what it is worth.
I have a Valterra that I have set at 55-60 psi, and haven't had any problems with five rv's at that pressure.

Don't know about RIVA but RVIA requires testing of the fresh water system between 80 and 100 psi. This testing occurs with the water Heater in bypass mode.

The pex piping is rated at 100+ psi & I wouldn't worry one second about the piping, but with the el cheapo Chinese plastic fittings used along with inexperienced folks installing the band clamps is definitely of concern. I bought the pex tool & tightened several of the clamps that were slightly leaking. Personally wouldn't want any more than 60 psi regardless of what RVIA rated it at.

AGREED !!!!B)