DSLC,
Congrats on the new rig!!!
As mentioned, in consideration of the potential larger tt in a few years, the biggest obstacle is usually payload of the tv. In the drivers door jamb there is a yellow sticker, stating "All passengers and cargo must not exceed XXX(X) lbs". This figure is the max rated weight that vehicle can carry. This includes all passengers, coolers, firewood, the wdh (up to 100lbs, or ball mount- not much weight for just a ball mount!), any accessories added to the truck after it left the factory (step bars, tonneau cover, truck topper, etc) AND the trailer's tw. While it will be hard to estimate a future trailer's tw, know that a trailer needs between 12-15% of the total loaded weight to be tongue weight for a safe, stable tow. So a 5,000lb trailer (loaded ready to camp) could have between 600-750lbs tw, plus all the other weight as mentioned. So just because a truck can "tow" 9,000+lbs, in regards to travel trailers you can see the payload, and a lot of times the rear axle rating, is/are the limiting factors.
A lot of the newer 1500/150 trucks have about 1,500lbs of payload per the sticker. GM's Twins have a little more it seems starting with the new '14 model. So depending on the passenger weight, and if you can try to estimate what you will carry in the truck weight wise, this will give you an idea of what may be left for the tw of the trailer.
For a possible future trailer, I would guess any of the newer 150/1500 trucks would be plenty pending verifying the payload listed in the door jamb of the truck. Just verify it has the tow package, and the best gearing that was available for the year for towing. Of course, if you want to take a core of firewood a 1500 isn't enough! Lol
IF you may consider a 5ver, a diesel 2500/250 due to the heavier motor can run out of payload because of the heavier pin weight a 5ver has compared to the tw of a tt. Gas trucks usually have more payload.
Future food for thought, the manufacture "brochure" weights for trailers and 5vers usually don't include options, even those "mandatory" options. And the "dry tongue/hitch weight" does not include the weight of the propane tank(s) or a battery.
Make sure you have a good brake controller. A Prodigy P2 or P3 is a very good choice from reviews on here. I was planning on a P2 to replace my old time based Reese controller, but we stepped up to a 2500HD that has the factory controller. Probably the most expensive upgrade for a controller!!! Lol
While you may not need a wdh with the current rig (pendingtongue wright, truck and receiver hitch/ ball mount and ball rating), the Reese HP Dual Cam, Reese SC, and the Equal-I-Zer 4 way systems are very good with integrated sway control.
Have fun with the new rig!!!