Given the fact that the farmer gets the grass and it needs to be kept in good condition for him, coupled with the fact that its really not that big, I would say the best thing is to give him a token rent every year and use the barn and land for your own enjoyment......maybe keep a few animals, grow a bit of veg, put some birds down for yourself......that type of thing. 
  
Put some artificials in for wildlife purposes....just enjoy it. 
  
If in theory you could do as you like, then I would have it as a horse retirement place  .......