You have a good truck for pulling that TT. As long as the WDH is set up correctly and the TT is loaded for enough tongue weight, the TT should have good towing manners. One does not need a 5th to have good towing manners but dialing in the set up is a bit more critical on a TT.
That looks like a good TT floor plan for a family and should provide plenty of space for all. My TT is point to bumper 30.5ft and I find I would not want any larger. That is a personal preference. When visiting RV parks, there are certain spots longer trailers will not fit into, 30 ft. is a good length to fit most spots.
I have been towing my TT into more and more remote areas and find I wish it was actually smaller. I now have interest in a TC but would like to keep our TT for family vacations too. What it really comes down to is your personal needs/wants and where you see yourself using your RV.