I've taken two long trips with the Tundra pulling the Globetrotter—west to Denver, Colorado, and then to Colorado Springs; and east to the Smokey Mountains. Also, last spring I pulled the Globetrotter to the Buffalo River in northern Arkansas where I camped at Kyle's Landing. The three-mile drive down to and up from Kyle's Landing has the steepest grade I've ever encountered (in fact, the park says that trailers are not recommended) but I had no problem.
I haven't taken the heavier Sovereign
on any long road trips yet, but I believe I could take her on any of the trips I've had with the GT.
When and if I need to get another tow vehicle, I'll probably look for a newer Tundra. I don't really like the newest ones, but the model you're talking about is exactly what I'd try to find. Good luck!
btw, My wife and I are excited about our next trip—we're taking the Sovereign
to a Vintage Airstream Rally at Elkhart Lake, Wisconsin. We'll be camping at Road America (a four-mile racetrack north of Milwaukee). The total mileage on this trip will be over 600 miles. I expect no problems!
another btw: I've had the Globetrotter for 11 years and the Sovereign for only 3. Once a person buys an Airstream, he or she wants another one! We now consider the GT our weekend trailer while the Sovern. is for extended stays.