This time of year, parks that are open probably have one of those freeze proof water spigots and there is no way to regulate the pressure on those, but if it has the round one like most, can't you regulate the pressure by not turning it on all the way? I don't know as that is hubby's job.
You might want to check with the campground before you go because they may have turned off the water for the winter with temps that low.
Also take a small electric heater and long johns, a feather bed, and or lots of blanket, you also might want to get a Little Buddy and a couple of tanks of propane. We love to winter camp but your TT is a tin box and hard to warm.
Happy first trip.