If you are going to write a letter, keep it short and to the point - don't ramble. Most farmers will have a lot on their plates trying to keep their heads above water without having to read some great long diatribe about how you can contribute to the fabric of society and can single - handedly reduce the entire crow and rabbit population on their land to mincemeat whilst maintaining the ecological balance...
If you want it, I have the text of a letter which I used to land permission for an 18-hole golf course. I can e-mail it to you if you're interested.