I have the same truck you. My trailer is 28' and 7200 gross (Passport 2800BH). I use an Equalizer hitch. I have scaled this setup loaded for a 9 day trip and I am at the trailer weight limit and my trucks axle limits.(we take a lot of stuff for the kids) The 9100 towing capacity doesn't matter in this case.
The truck tows nicely at highway speeds. Obviously it kicks down for hills. The truck drives nice and tows good unless my tank is full of water (I need to adjust my hitch) which I have been able to avoid this summer.
I would not go longer or heavier based on what my experiences are. The 7200 trailer would definitely put you over your weight limits. There are plenty of people out there that do, but I don't think you would like it.