I am a HUGE trooper fan. I have two in the yard at the moment, but I would never recommend anyone buy a trooper with an automatic transmission.
My 98 with OEM 5 speed is great, I love it, but like every isuzu I have ever had (I have had 5 through my life) it hates reverse. I think they are geared too high, at least those with the 4l30e (only v6 auto ever available in a trooper) and the 98-02 5 speeds, maybe the 4cyl auto or 97 and earlier 5 speeds were different.
Isuzus burn oil like its going out of style. the 3.5 is most known for the issue, but every Isuzu I have had burned oil even when they had really low mileage.
They have dana 60 rear ends, disc brakes before their time, 3/4 ton frames. Amazing machines but they have enough quirks that you need to be an enthusiast to keep it on the road.
Since we are in the nissan forum I will say a 2nd gen xterra is probably as close as you can get to a trooper. 2010+ doesnt have the transmission, radiator issue the 05-09 have. Available factory rear locker, disc brakes in the rear (toyota, drum brakes on a mid size truck in the 2017 year model, really?)
Regarding "long range" the trooper does have a 22 gallon fuel tank. You need that considering most average 12mpg on the road (I can get 19 even in an automatic but it takes a lot of work and patience) 12-16 is to be expected with normal driving. Less in low range (obviously).