Well, I think you should certainly supplement with some type of readily
available grass hay. Horses are grazing machines after all. The problem
with pellets isn't nourishment, but physiological and psychological
healath for the horse. If they don't have much chewing to do, they may
develop some bad habits...such as chewing up the barn or fencing (though
I'm guessing there won't be much access to wood for your partner). If
your horse has access to pasture daily, the grazing need will naturally
be met. I don't know where you live, but 2000 acres of riding sounds
like it might be a pretty good deal for you. Supplement the horse and
enjoy those trails.