Welcome to the forum and, the A/S family`!
For your water pressure, several things. You could check the in-line filter trap located near the pump..Make sure it's been cleaned. (Rather simple to do) Accumulator tank can be add to your water system quite easily. While this may not "up" your pressure, it will keep the flow steady for you. (Another simple and, easy do-it-yourself project.)Check this site for large selection of water pumps, filters, accumulators, etc.
You might even consider replacing the shower hose/shower head.
Water Pump Accumulator Tank
Lastly, I can say based upon my own experiences. Whenever possible, I use the shower at the campground`! Saves on water heating cost.`
Again, welcome to the forum~