Keep in mind...a 1/2 ton truck in the upper payload ranges is well within capability for towing a 30ft travel trailer. (1/2 ton payloads vary wildly so you need to be toward the upper end of options).
For a 30ft+ 5th wheel, you really want to be up to at least a 3/4 ton.
The reason is travel trailers ideally have 12-15% of the trailer weight on the hitch. 5th Wheels ideally have 20-25% on the pin...That means lower payload trucks run out of payload quicker with a 5th wheel even if they have enough engine to pull it.
Since you are buying the truck anyway get a 3/4 or 1ton single rear wheel after checking the GVWR of the 5ers you are looking at (take 20-25% of the GVWR as an estimate of pin weight). Even with a travel trailer moving up to a 3/4 ton is a nice option and really doesn't cost much more compared to a 1/2 ton optioned out for max towing capability.