I would pass, because of its former life. I know I worked landscape for 3 years, and we used our trucks the same way, and we worked them HARD. Snowplowing is especially rough on the truck. When you do it commercially with a truck thats not yours, and you've got 10 hours of plowing ahead of you, you fly, reverse-to-drive slams, hit curbs, etc, plus, as you noted, the salt can corrode things bad.
For reference, that white dodge of mine (96 3/4 4x4 V10, 115k miles) was $5k. The deals are out there, if you look enough.