I agree that a 35mm (or wider) rear tire is appropriate. I'd suggest going down to a 28mm or 32mm tire on the front. With your unequal weight distribution, your front tire is quite lightly loaded and you could have nearly as cushy a ride with less rolling resistance and better handling by running a narrower tire up front. I tour on the road with an all up weight of 230lbs with a similar weight distribution to yours. I use a 32mm Panaracer Ribmo on the rear and a 28mm Panaracer Tserv up front, both running at 80-90psi. Though they are of different sizes, the tires handle similarly because of the different loadings.