Olympus - You've been given a LOT of GOOD ADVICE in this thread but it sounds like you've already made up your mind to do this. I'm going to repeat some of the same advice just because I think you need to hear it again.
First, in spite of what you may want to think, this will be a REAL BUSINESS!! Someone is paying the current guy to do this. Is it your Homeowners' Association? (HOA) If so, the HOA is
required to report what they're paying people for services to the IRS. You will get (or should get) a 1099-MISC for "non-employee compensation". You will need to report this income on your income tax return on a Schedule-C. You will need to pay income tax on the income as well as "self-employment tax" which is actually social security tax. The self-employment tax is about 15% plus the income tax on it. Even if you don't get a 1099 from the HOA, you are still REQUIRED BY LAW to report the income. If you don't and you get caught, it could be considered tax evasion. You won't go to jail, but it won't be a pleasant experience. There's more to the reporting stuff that I won't get into here. Someone above recommended getting a CPA. I'm a CPA (I don't practice anymore) and will tell you again - get a CPA! (That's yet another expense!!)
Second - Get insurance. You will break or damage something that belongs to someone else. And someone else will want you to be responsible. Yeah, I know it's your neighbors but they don't want to be paying out of their pockets. Neighbors can be a**holes, regardless of what you want to think. Once you start taking money, you're no longer "doing them a favor", you are "charging for a service". That means that the recipient of the service (formerly a favor) goes from being a friend/neighbor to being a customer. That also means that your work is going to be critiqued by the HOA. If they decide you're not doing any better than the current guy, you could be replaced as well. What then?
Third - As someone else mentioned, RUST!!! I live in the saltbelt too so I do know a little about road salt and rust. There is NO WAY that I want salt around my tractor! While I was looking for my tractor I enlisted the help of someone that I knew who also happened to be a former lead mechanic at our local Deere dealer. After he checked out the tractor that I ended up buying, he pointed out another one that was in the lot. It happened to belong to a local landscaping company that used it for exactly what you want to use yours for. He pointed out the pitting in the tractor frame as well as the hydraulic lines. He said that once this starts you can't stop it. Replacing all the lines was in the cards for that tractor. So, if you do this, be sure to charge enough to factor in job related repairs to your tractor. That's why the other guy is getting what he gets for each trip out there. It may sound like a lot of money to clear your road, but once you factor in taxes, insurance, repairs, fuel, salt, etc., etc., etc., etc., there ain't much left over! Speaking of repairs, a buddy of mine that clears roads with his truck just had to replace the frame of his plow ($1600) and the transmission in his truck ($2100). Are you considering stuff like that? Also, what if your equipment is down for some reason and you get a big snow? You're still responsible for clearing that road? Do you have a backup plan? (sorry - I digressed! This paragraph was supposed to be about salt! :laughing
I could go on and on, but hopefully you get my point. I'm not trying to discourage you, but I (and others here) want you to be aware that there's much more than just having someone else pay for your tractor. If you want to start a business, start one! I've been self-employed for almost 23 years (not to mention the little business that I owned while I was in college) and wouldn't trade it for anything. I made a LOT of mistakes during those 23 years so I'm trying to give you some of the experience of this gray haired guy!
Good luck with whatever you decide!!