Like Miltvill said if you have a locking rear axle or limited slip you should be fine without 4x4. 4x4 is for getting stuck, if you are towing you just need limited slip/posi-traction/locker hubs on the rear and common sense.
Most people think their truck has a no/limited slip rear end and it does not. One tire starts to spin and they are stuck. Same with many "4x4"'s if they do not have locking axles or a limited slip then the 4x4 becomes 2x4 spinning two wheels.
I have towed with both. I had a 4x4 powerstroke ford and now have a limited rear end Chevy. My limited slip, with the 5er sitting on the rear axle, performs as good as the 4x4. The only time I ever got stuck towing was with the 4x4 because I thought it would pull through and did not. When the mud is deep all the tires spin. I have used chains on the 2x4 and it performs like a half track even in 4x4 stopping clay.
BTW: I had a front wheel drive Civic in Germany which would go up snowy/icy roads that stopped my Army issue jeep when in 4x4. It is all about weight and traction, not how many wheels you can make spin ;)