Second 4x4 truck and use it all the time when towing.
Since I camp exclusively at Provincial and State parks all the camp site roads and sites are hard packed gravel/dirt. Throw the truck into 4x4 Low and can walk the truck into a spot without even using the throttle. She will easily push the trailer and truck uphill without any strain on the tranny and no messing with the throttle. Idle will get you where you need to go without any sudden starts when burping the throttle to get it to move.
I also winter camp a LOT and of course have towed in 4x4 High lots of times. Wouldn't own a pickup without it. Have a 2wd F150, hate driving it in the winter, even with snows and 500lbs of sand in the box.