No water in fresh tank, no, though you may get sputtering due to the addition of air to the lines.
Parks vary, where I park in the summer 50-60 PSI is common, where I am now.. Double that (YES 100-120 PSI) the house pump, about 45-55.
However if you 1: Fill the fresh tank and 2: use an IN-LINE filter (Which I seriously recommend) the filter may restrict flow enough that the on-board pump makes a big improvement. Also pressure regulators (Very needed where I am now) I have tested several
Standard (3/4 inch brass or plastic cylinder, Female hose end on one end, male on other) 50 psi Static, WIth the shower going I have to look real close to read the pressure it is that low.
"High Flow" Like above but usually has a bright plastic grip on the female end (Camco has wings on the body) Slightly better but not much.
Sur-Flo Mine is old, and likely needs rebuilding but shower took it down to like 10 PSI
Watts 3/4 inch, Older than the Sur Flo, it hit 20 Again I suspect a rebuild is in order however due to damage from frost... Not sure I want to do it.
Brand new ZURIN 3/4 inch
Static: 50 psi
Full flow on outside shower: 50 PSI. No change that I could see.
Some day I'll likely re-build my watts.. Routine repair kit plus find one missing part.. If I find it I will re-test with it. I suspect with a new diaphrham it will perform identically to the Zurin. Perhaps better.
Home is where I park it!