Here's another in favor of using 4LO, especially coming down! Inching down a steep trail with 20K+ pounds can be too much for your brakes. (Ask me how I know.) ;)
Yes, I did it once. I had a 2500 lb. slide-in camper on an F250. I'd been down that 4x4 canyon trail dozens of times before, but this time my girlfriend (now wife) was riding along. She's scared to death of steep and narrow mountain trails, so when she started freaking out I slowed down. I don't remember whether I was in 4LO or 4HI, but I'm thinking it must have been 4HI, as I rode the brakes a little too much... and suddenly they were GONE! Luckily I was almost at the bottom of the canyon when they left me, and I was able to find a place where I could leave the trail and head up a little hill until we came to a complete stop. Were it not for that little hill, I'd have been plowing into cars, people, or maybe a very swift stream.
And you're talking about doing it with a 14K trailer. Don't do it in 4HI! If this is a 25% grade, you need 4LO. This is why you have it.
As for the front tires grabbing in a turn, let 'em. On a dirt road it's not going to hurt a thing.