Thanks all for the suggestions so far. The issue isn't that she's on the boat and needs to go. If that were the case, a She-wee and bottle would be my solution for her. The issue is that the only boats she's interested in me owning are ones that are big enough to have a bathroom. Toxic hits the nail on the 'head':
That was the implication on saying bathroom. Basically a boat with a head will probably have a bed too. At that point, you're pretty locked in to a style and that style isn't an aluminum fishing boat. BUT, she said bathroom so I'm eventually going to figure out something clever. At the last stadium concert/tailgating we did one of the people brought a tiny bathroom tent, maybe 4' tall, in case the portapotties were awful or a long walk away. This might be my lead candidate so far.
The thought of a pontoon boat has crossed my mind. I can't fit a full size one, but the mini pontoons would be interesting.
depends on the trailer a bit. Lots of newer boats/trailers have been moving the boat forward on the trailer and shortening the tongue. Then putting the pivot right under the nose of the boat. As gimruis noted, you get about 18" back that way. On an older trailer with a long tongue you can put your own pivot in and save a little more. At the end of the day though, 16' of boat plus 2' of motor is about the limit on my garage if I want to be able to slide past the front of it. Also, a 16' boat normally will have a trailer width less than 8'. When you start hitting 17 or 18' boats the trailers get wide. A tracker TXW 175 would just squeeze into the width and be a touch long (might fit if its turned diagonal). I really wanted a TV18 and was ready to get wheel sliders to turn it diagonal across two bays, but the wheels are right on 96" wide.