I know I can be ignorant sometimes... but I feel like I'm missing something... most of you are telling this man to go buy a planter.  Unless I missed something, he's not even going to get paid for his time.. That's like saying build a barn so your neighbor can keep some cows in it.. and oh yeah, you can feed them for me all winter too, I'll pay for the feed, you just be sure to go pick it up and keep them fed.  Someone talked about marketing.. what marketing?  If "they" are paying all inputs and taking all income, I don't know that I would want to be responsible for why I didn't get an extra ten cents a bushel so-and-so would have gotten if they had made the contract.  Humans are a poor match for their greed.. and they don't care whether or not they're paying you if they think you cost them five bucks somewhere.  Yes... this is an opportunity for someone with no other avenue to get to operate machinery, and maybe see if they want to pursue something else on their own... but it's not "farming".  When you're only an operator, it all comes out looking like roses.  Breakdowns?  No expense.  Bad crop year?  Don't feel it.  Crop insurance premium?  Don't pay it.  It's like driving a sports car with no fear of wrecking it.  My honest suggestion?  Find a way to convince them that you want in the game.  Find a fair price for renting the equipment and do a crop share on the ground with your labor inputs recognized by some share % of the crop.  That shows good faith to them as well that you have yours AND their best interest in mind when making decisions such as when to spray, how often to spray, selling the crop, etc.  You will unconsciously put more thought into things if there is some monetary incentive on your end as well.  I don't know the best way to work it out, but I do feel that getting a "stake" in the process is the only fair way to both parties.  At this juncture, it looks like they're getting 80 acres put out with zero time or labor investment, which is a very sweet deal... for them. 

I believe with the time you say you have available, you have the equipment to do the job.  40 years ago around here people were farming much more with equipment that size, in much smaller pieces (less than 30 acres in a field commonly), and many working full time as well.. Not saying bigger equipment doesn't make it easier, but it just doesn't make much sense from what I can tell of your situation right now.  I know there's more to the story than a couple paragraphs can tell, I'm just going by what I think I read.