The wife and I are ER'd and looking into doing something like this eventually, but honestly, the upside for the person working there sounds pretty low.
Like, you're looking for someone already self sufficient (early retired/financially independent) to work for free improving your farm/business to make you money, and they, in return, get... free lodging?
And the work that sounds required is far above and beyond the simple "maintain a farm," but infrastructure, business development, and growth.
You mention, briefly, "percentage splits"--it might be worth it to elaborate more on why someone would want to do this, because there seems very little benefit/upside for the person you're looking for.
Like, I can see plenty of young people who earn money online, are broke and don't know better being interested, but you preclude that possibility by requiring them to already have independent income without needing to earn more online.
I can't see people already FI wanting to do this with so little benefit. Essentially a full time job, for two people, that nets them around 12,000 (estimating living costs/utilities at 1k/mo in a typical ER'd budget)? Or $6,000 annually each, for a full time, physically and intellectually demanding job? Assuming 40 hours/week (though I'd bet it would be more), they'd be making something like $2.90/hour.
At that point why wouldn't they start their own farm like this, and work on their own opportunities? Thus my comment about young people who want to live abroad, make a little money online, and not knowing better. But the already ER'd couple with resources can buy/start their own and have ownership, rather than working for very little.
I'm not trying to offend you--I'd actually like to learn from you, because we're looking at settling down and doing something similar with our kids (we had been thinking Belize, but Costa Rica is on the table as well)--we just ER'd at 30, and are having our first child in the next month. We're traveling the world full time right now, but were thinking about settling to an off-grid homesteading/small farm type living to raise the kids at some point.
I'd love to hear more about your experiences, especially as it relates to the kids.
I'm just trying to explain how I see this, at first glance, and likely how others will, so perhaps you can tweak the opportunity, or explain it differently, if I'm missing something, highlighting why one would want to take this job at such low benefit when they're already FI. Hope that makes sense. :)