86
I've been in this situation a few times where I have something hanging out the hatch of a car. Often, there isn't really anything to hold the hatch down. But at slightly open positions like this, the handle for the hatch is perfectly oriented to clip a bungee cord on and hold it down.
Is this just a coincidence? Maybe. Still pleased me when strapping it down in the parking lot
I do wish there were actually a hook of some kind, though, for when it's significantly more open. Not that I've actually needed that.
Should the rear seat striker be used to strap down things?
depends on what your concern is. the strap tension load isn't harming it at all (mostly internal forces), and the inertial force of the load in regular driving is more or less in line with what it would experience in a crash with somebody in the seat, except much lower load
there's a little bit of twisting on it when hitting bumps due to the unsupported middle of the boards, which is admittedly not great, but I'm not concerned at that at all because I pretty much never have passengers back there, so the chance of having a passenger, crashing in a way where this has been weakened enough to fail, and for it to fail in a way that makes it worse for the passenger is just not something I'm care about lol