I live in Florida which is probalby the flattest state in the country. But i have friends that put 37s on their truck with 6" and bigger lifts w/o first regearing and they complain all the time. Even driving down interstate 95 at 75 they say that their truck downshifts just to go over overpasses. They all say it will be the very next thing they do. one of them even took a second job for the sole purpose of getting gears because he hates it that much.
Do it right, or dont do it at all. You will regret it if you dont. It will look really cool, but when a honda civic can beat you on the road and in the mud, you will realize you should have saved the extra 1200 for the 4.56s or the 4.88s.