Are you considering the S-10 for gas mileage reasons. If so, you may want to reconsider, due to the fact that the smaller engine will have to work harder to pull the weight increasing fuel consumption.
Consider a full size truck with a V8 engine, the fuel economy will be close, and you'll have the advantage of more cargo capacity, bigger and better brakes and the torque to pull a boat out of the water.
Also, with everyone downsizing and the cost of fuel going up there are some good deals on full size trucks right now.
Thrifty, Check the mileage difference closely before you buy. I've owned a Bravada with a 4.3 vortec v-6 and while it towed great the gas mileage was not that much better than my GMC 2500 crew cab 6.0 for everyday driving, or my Dodge 3500 360. All these are going to get between 15-19 mpg.Considering that model for better gas mileage on an everyday basis. It would be used on rare occassions for boat towing.