The Ranger is a capable towing vehicle provided it is equipped correctly. If your going to tow close to maximum limits I strongly recomend getting the 4.0 SOHC with the auto trans.
But, like was said above the Ranger is too small to dafely tow a larger boat as you cannot see around it. Also it is a little light for bigger boats too. Remember getting going is the easy part. Stopping and control for sudden turns is quit another.
Rangers are far from fuel misers. The SOHC might, and I repeat might, get 2mpg better than a 4.6 V8 in an F-150.
The biggest benefit the Ranger has is the compact size and ease of driving in traffic. Reliability wise they are very good as well. Good luck!