I use an 18' x 60" modified v jon boat. I absolutely love it, but there are times I go through fairly big water.

With 3 guys, I would side with a 16' with a minimum beam of 48" (you should be able to find 52" or maybe even 60"). I don't think this would be unsafe, unless your going into really big water. Certainly if you're staying in marshes, it won't be a problem.

If you're going to be in the marshes a lot, either go with a mudbuddy type motor or a two stroke.

Good luck,