"We have a front bathroom in our 16 ft Scamp-toilet and sink...we are considering, yes I said considering, trying to add a shower somehow!?!"
is a little different than your's but I've considered increasing the size of the bath in our Scamp
16 with the side bath.
I would shorten the couch to two thirds of it's length, removing the section behind the side bathroom. I would extend the bathroom to the front wall.
I would then move the toilet to the former couch position and convert the former side bath into a virtually dry shower.