That should be the perfect truck for what you want to do. I have a slightly smaller version of that truck, a 92 Kodiak. Mine has the smaller, 3116 Cat engine and a 10 spd trans. I can run up and down hills, towing a heavily loaded tandem dual gooseneck full of firewood, at 65-70 mph, with no problems. My truck, trailer, and load, are grossing about 35,000. I never have to shift out of 10th, even on long uphill grades.
The price sounds good too. I would really say that might be the deal for you now. You can always upgrade to a larger truck later if you need to.