Joyce, a route you may want to take is by signing up with the WWOOF organization, there are several similar organizations as well. WWOOF, Help-x, and Workaway. You provide food and
shelter for folks in exchange for help, the trick is to be very up front with everything and don't try to sugar-coat it... However, I would keep the land/trade thing under my hat until you met the right person. We've had SO many great volunteers here over the years, it's been awesome! It would also give you a wonderful opportunity to interview folks for the ad you just placed, if someone seems like a good fit after spending some time with them, then you can make them your offer! I worry about someone being less than honest showing up for your ad, looking to get some land and not being really great to have around, if someone thinks they're going to get something, they can put on a mask for a while and fool us into thinking they're not the person we hoped they were, but by having someone show up just to work and help out with no mention of "free" land, I think you would get a much better type of neighbor out of that deal...
Good luck!