[SheepWhisperer]

Stainless steel hose clamp on hinge.
Rotate the tightening nut inward to minimize accessibility.
Once tightened, apply jbweld/epoxy to nut and clamp area to prevent loosening.

Doesn't completely prevent theft, but does make it very difficult, noisy and time consuming to steal the tailgate and didn't interfere with functionality of the gate...EXCEPT removing it.

[Carriage Hill]

“...steal the tailgate...”

???
Are you kidding? I’ve never heard that one.