It's my understanding that you can take your purchase records to a court, file a complaint against an unnamed party, provide evidence about the current location of the property, and use that to get police intervention (for which the sheriff's department probably charges a fee). This process is needed because you owe the public a duty not to breach the peace, for instance, by breaking down a door and prying the property out of someone's hands.

"Wouldn't a criminal charges of some kind have to be made instead of the process say, a car dealership goes through to repossess a car?"

Unless you want vengeance, worry about getting the property back, not about the crime.

Suppose the buyer of a bass boat dies while it is stored in a rented garage. No crime has been committed, but it will take a court order and a deputy with a bolt cutter for the repo man to get his hands on it.

"Is rent-a-center allowed to surreptitiously record it's customers in case they don't return stuff (without notifying them and/or getting a signed waiver?)."

No, that would violate the implied warranty of fitness for purpose of the merchandise.