Right... as suspected by Twoxentrix, water pressure is a bit low. We use the tank mainly for storage of non-potable shower water. Then transfer to a bag that I hang from roof rack with hose and shower head. Battery powered pump is an alternative... no transfer of water.
My aluminess isn't tall enough but I always thought something at the top of the open rear doors with a bent pex tube would support a light curtain. That setup is nice though, I'll need to revisit this topic if I ever get around to this.