I've been turning this thing over and here's what I've got for you Tommy. What you're dealing with here is a rare breed of bold transvestite homosexual.
As a weightlifter, I'm sure you've run into the occasional queer giving you the eye from time to time. I'm guessing that this guy "noticed you" and convinced himself that if he turned up at your place in his sexiest outfit that you'd want to tie him to a post on your power rack, seeing as he had it all set up and ready to go. I'm guessing the wire was intended to go around his throat and the plastic & duct tape were padding for his face or head. Or maybe the plastic and duct tape were meant for suffocation and restraint. Who knows. But he jumped out and showed himself to you when he could have simply stayed hidden. I think he was hoping for an invitation.
At any rate, he saw you get angry and reality probably overtook his ya-that'll-happen fantasy for a moment and he took off. Why he came back up the hill is a mystery. Maybe he thought you were waiting for him in the house with a margarita. Maybe he left something behind and wanted to retrieve it, like his normal clothes or shoes. Have you looked around carefully?
It seems unlikely that he was a wandering weirdo. You couldn't wander very far in that getup without being noticed and arrested. Looks to me like he chose your place for a reason, and I'm guessing it's you, you big stud.

So maybe he's a local, and with behavior that bold I'd bet he's got a record of sexual deviancy or at least the local buzz will know who the town fruitcakes are. Or it's someone from the wide world of this 'sport,' a schmoe housecall. I seriously doubt that this was random tho. This guy picked you.
If he wasn't wearing any gloves he probably left some prints on the rack, the plastic wrap or duct tape, or the back of the truck he was crouching behind. Hopefully that will lead the cops to him if he has a record. If the area is rural, he certainly didn't walk there, so consider where he may have parked given the direction he was running and snoop around. Maybe look at car rentals and local hotels/motels if he's an out of town schmoe.