Some 1/2 ton trucks will not have any problems towing a 7200 wet weight trailer in the mountains.
In fact some 1/2 ton trucks will have superior engine performance/power in the mountains or high wind flatlands over most 3/4 ton gas trucks.
Example is Fords F150HDPP at 8200-7850 gvwr and 4800 rawr with a 3.5 ecoboost engine rated at 375hp/470 torque.
Now if your 7200 lb trailer is a dry weight then a 3/4 ton gas or diesel make better cents/sense.
That 7200 lb dry weight can have a 10k gvwr. These size trailers can have 2000 lb plus pin weight. Now add another 200 lbs for a hitch and another 100-300 lbs in the bed = maybe 2500 lbs on the rear axle. Not a good match for a 1/2 ton truck.
A 3/4 ton truck with those big 6000-6500 rawr can safely carry/stop 3000+ lb rear axle loads. Actual numbers depends on truck selections and actual scaled axle weights.