Using the campground showers certainly depends on the campground....I just finished a wonderful 30 minute shower and never had to concern myself with running out of water, filling up the tanks or running out of hot water...but the campground I happen to be in has by far some of the nicest and cleanest bathrooms I have ever seen. And I say bathroom, it is a full 10 foot square room with toilet, sink and vanity, place to sit down and a full sized home shower, with plenty of hot water and squeaky clean. It is one of the reasons I stay here and will make a pint of returning. Nice tile floors locked door and your own private full sized bathroom...hard to beat!
I use my shower in the RV from time to time, boondocking or when in a campground that has shared type showers or ones that I don't feel particularly enthralled with the cleanliness. But when I do it is a navy type shower, which gets the job done but more of a struggle.
I lived on a 40 foot sailboat for years and have over 75 thousand miles on the water and most marina bathrooms are marginal at best, so much like my RV it was quick Navy showers and you get used to it, but if I have a choice, I will put my crap in a bag and walk or even drive to the showers and relax and enjoy my nice long shower....I am shopping for a newer 5th wheel and one of my requirements will be a little bit larger shower and a larger hot water heater, but given a nice clean campground shower, then that is where I will be!
It is really not a huge issue, it may seem like it, but you will get used to using less water and dealing with confined spaces, that is just RV life or boat life....they are very similar.
Good luck...
Jim