Whisk together the lemon, olive oil, honey, salt and pepper. Set the dressing aside.Add the watermelon, cucumber, red onion and basil to a large bowl. Pour in the dressing and toss. Let the salad sit for about 15 minutes in the refrigerator to marry the flavors. Add the feta in last and toss it gently so it holds its shape.Serve the salad just the way it is or over a pile of fresh greens.