If you are away from home, and not able to attend hens every day, then thats not a good idea to have them, unless you find someone to feed them for you. In all my stuff from DEFRA, it does say that all livestock must be fed every day, and personally hens need feeding twice a day if penned up. Something could happen, their water or feed may become contaminated, or the hens themselves could have an injury or get stuck - I know from experience the things hens can do!!
Is the land flat - could you have tents or caravans on? The caravan club quite often have rallies, bringing only 5 caravans. All self contained, no loos or anything required, just a water supply maybe. That would bring some money in. We often get asked by dog clubs, wanting to do agility etc. and they want a small area of land, and will pay, as will model aeroplane clubs etc. just thinking these things would be easeir than hens, horses etc.,