From the magazine Mustang I, from the Cosco film Mineshaft
Director: Steve Scott (1984) 80 minutes running time
Starring: Lee Ryder, Jon King, Eric Ryan, Michael Carr, Robert Vega, Brian Palmer, Champ Larue, Mike Braun, Danny Combs
Lee Ryder, who plays a drifter, stumbles upon a western being made in the California desert, and begins an affair with the star of the film, Eric Ryan. And at some point, has sex with Ryan’s personal assistant, Jon King – shown here.
and a nice 4-minute trailer over on Manhunt