I've always lived on the coast. A boat could make sense as a bail out vehicle, in certain circumstances. When I lived on the Outer Banks of NC, we were often evacuated when hurricanes were approaching. This would usually mean several hours of sitting in traffic. I owned a 20' foot center console at the time. Everytime I towed it in the heavy, evacuation traffic I thought about how much quicker I could have gone by boat.
If you live in a city by a large body of water, I can about promise you that you'll make better time on the water, getting out of town, than by fighting traffic in a shtf scenario. A larger boat would also act as a base camp and a place to stay until things return to normal.
As far as being a "great target" goes, anyone who is better off than others in a shtf situation is a possible target. A boat can certainly be defended and might offer more mobility than something like a camper trailer. You have greater visibility on the water, which makes it easier for one person to keep watch. You will probably run into far less people on the water, and the people you do run into are liable to be of a better quality. Your greatest danger would be when you had to come ashore.
I assume you live by one of the huge man made impoundments in Nevada. If you lived by the coast, I'd also suggest you consider a sailboat. Motorboats of any kind are not exactly fuel efficient, although a modern fourstroke gets pretty good "mileage".
I'd certainly rather be "chillin" on my yacht, up some small protected creek, than cramed in some temporary evacuation shelter. It would also get you away from the type of public officials who think it is okay to disarm Americans during emergencies. I can't believe they actually re-elected that guy.
Good topic