HWY: An American Pastoral (1969), in which he was the main actor, and the producer. It stayed quite obscure, but supposedly it can be found online. Here comes an interesting -"interesting" is a euphemism for "shocking" here- opinion of his on Cinema; very provocative wording and equally provocative choice of a certain despicable historic figure to draw parallels with. Uhm, the truth in it is certainly disputable, but up to you what to make of it.
“Cinema is most totalitarian of the arts. All energy and sensation is sucked up into the skull, a cerebral erection, skull bloated with blood. Caligula wished a single neck for all his subjects that he could behead a kingdom with one blow. Cinema is this transforming agent. The body exists for the sake of the eyes; it becomes a dry stalk to support these two soft insatiable jewels.”