I use wwoof and with a good application it's been great. You do have to
feed wwoofers. If you're interested in seeing my application, send me a purple moosage with your email address. You might ask different questions than I do but the concept is good. Many puerile don't even fill out the application and red flags stand out on some that do.
If I was making a long term agreement I'd want at least a trial period and maybe a contract/lease