There are options for the shower. You could setup to use an outdoor shower if you're going to camp in the boonies a lot. New AS have outdoor showers for use hosing off the dog or feet before entering the trailer.
If you're going to camp in parks a lot, most of them have showers, and I'm starting to find it really is easier to go drop a few coins in the public shower and not mess up the caravel
. I think a shower is one thing you could really work around, considering how little time it gets used, and it takes up a good amount of space.
I would generally advise keeping a really perfect interior original, as I think it helps with resale value down the line. But if you make changes to make it more useful to you, then that's what's important. The next owner might agree with your changes! If you do leave out the shower, be sure to save the pan. They are like gold - hard to find and hard to replace.