Buying first TT - New or Used?

We bought a new bunkhouse last year for our family of 4. It was our first TT and my wife was a bit apprehensive about the entire idea at first but it didn’t take long for her to come around and she really loves it! I was apprehensive about buying a used TT because I didn't have many friends with TT knowledge to help me at the time and I wanted a something with a warranty. Our TT is great for our family of four (our two kids are 6 and 10) but it does get a bit cramped in the kitchen area. Eventually we would like to get a TT with a slide as our kids grow and as they start to bring some friends but a descent sized slider maybe on the borderline of the capability of a half-ton TV. I can tell you pulling my loaded TT (4365 lbs dry) with my 5.3 Silverado and 4 speed is not bad on open, flat roads but it’s not a great experience in moderate inclines. I think if you went with the Keystone a newer 6 speed 1500 or a 2500 (3/4 ton) would be better suited to pull that weight. As others have said, you will probably run out of payload capacity with that weight and a 1500.