many folks will have advice for you on the right bike. make sure it fits you and don't worry too much about your weight. most touring bikes can handle plenty of weight. they just get a little different feeling is all. your goal of 40 miles per day is very doable and quite sensible. i would also say if you can't fit everything on the bike without a trailer you are probably taking too much.
the main thing i want to say is congrats for making the commitment. it will change your life for the better. you almost couldnt pick a cooler or better way to improve your health, and its a gas!!!!