8 feet is plenty of separation, but that's between each pair of plants. If you are talking two locations 8' apart, only plant one variety per location.
Remember one unassailable statistic, as explained by the late, great George Carlin: "Just think of how stupid the average person is, and then realize half of them are even stupider!"
"I would like to die on Mars, just not on impact." Elon Musk