We had this discussion at our house this past spring. Dearly loved our HTT and no water issues, but age crept up on us and it was getting to be more of a chore than we wanted. We also have the F-150 CC 5.4. Our max is 8000#.
There isn't a huge selection to allow for 4 to sleep between where you are now and where you'd like to be. We found the Rockwood Ultra Lite 2604 perfect for us. BUT, something like that requires either the bed or sofa be made up for the extra 2 unless you go to a bunkhouse. Our GVWR is 6629 on the new TT.
Suggest you get a comfy chair and start looking online with RVwholesalers and RVDirect. They both sell many different brands, floorplans, pictures and sometimes video. Most times they have specs, but not always complete ones. You can get an idea of what's out there and then start a search for the specific models you might be interested in. If you're interested in either RVW or RVD, there are many satisfied campers on these forums. We bought both of ours from RVW. No games. They show an MSRP and will email you the actual price quote but you can guestimate at about 30% off and be pretty close. Allowing for travel expenses, on our HTT we still saved over $4000 and more on the TT. Save yourself some driving around. If you decide to buy locally, you have a good negotiating tool by printing out their quote. Happy shopping!