I think the extra length while towing would be more than offset by the extra 3 ft. of interior space especially if some of it went towards the bathroom. Our trailer is 30 ft. and we find it comfortable for two with the 1 to 2 week trips we take. IMO too small for full timing. We have been to only one site (Fishing Bridge) where another 3 feet would have made a difference. You might find that towing longer will be smoother as the pin to axle distance is a factor relative to chucking.
Good luck shopping, it should be enjoyable.