After a recent stuck-in-the-mud incident I'm considering buying a winch for my Jeep Wrangler. Here in the Northeast, though, everything is covered in salt in the winter and subsequently rusts. Bolt-on parts for vehicles seem to be effected worse.
What, if anything, can be done to prevent a winch from rusting?
Buy a quality winch.
Winch manufacturers know that thier product will be sitting on the front bumper, and getting the brunt of the road/trail.
A good winch will be sealed against the elements.
I had a Champion 7500# winch. Bought it for the price ($250, and included the universal mounting plate)
I went through 2 motors for it, in 5 years, from corrosion.
Each motor cost $100 plus shipping, so my 'cheap' winch, cost my around $500 for 5 years of use. (motor just went out again)
I have a WARN 8K on my CJ now, and it's holding up great.
Buy a quality winch, keep it clean, and it should serve you well.
Make sure the motor is a 'Series wound' style, they hold up better to the elements, IMO.
You can also use a neoprene cover over the winch. It won't keep everything out, but it will help. And work well with proper maintenence. (pulling the cover/washiong the winch off, etc.)