Actually, depending on how you set the turbo up, it could be very useful in wheeling, especially when you need that extra "umph".
I am considering (and will eventually) do this to the four raging squirrels in the TJ.
Most of the time when I really, really would need extra power, I'm in the optimal RPM range as-is.
However, a properly setup turbo system can easily come on at lower RPMs. Sure, it's not necessarily as effective as a supercharger, but still can be quite effective. A smaller turbo will give you more of the low end power, and not so much topend. A large turbo will give you big boost at higher RPMs, but not the low end... I've read damn near every piece of info on turbos that I can get my hands on, and trust me, they can make bigpower and still be quite fuel economical.