I was in a somewhat similar situation as the OP, but with an existing trailer and under performing tow vehicle. The trailer, right around 6000 lbs fully loaded for camping including firewood. The tow vehicle, a 2003 Chevy Tahoe LT with tow package.
A question that is appropriate; what sort of towing, and where will you be towing? Will you be primarily on interstates to your destinations? Or will you be travelling the back roads? Any mountain driving, either east, Rockies, or west coast? Or mainly flatlands? Or a mix of both?
In my situation, a lot of mountain driving is involved, both now as well as in the future. So I opted to buy more truck than I would need. Bought a 2007 GMC Sierra SLE 3500 dually. The diesel is certainly up for the job, and after a 2000 mile recent trip involving high desert as well as high mountain passes, I know I made the right decision FOR ME. And with trips in the future involving passes in the 10000-12000 ft range, having more truck than I need will give me more peace of mind, in comparison to "trying" the same thing with the Tahoe.
So I would suggest that, if you're looking more long term, get more truck than you need for now. I don't think you'll regret that decision.