We did see some trailers with atvs and some big rigs but did not notice any excessive “running around”. I think it’s mostly a launching point for other spots. We were not disturbed at all (but have cats…no horses :) )

When we camped along this road, we were the only campers with dirt bikes, no ATVs, and we set off on bikes from the camping area to hit surrounding trails. That was in September of 2020.

We saw some ATVs in the area, but it was not full like some other places

Not so much. I only saw one during several days I was there. I think you would be fine with horses … plan ahead for water, none available here but maybe in town.