KJ Cargo hook bolts

[joooooooooop]

I’m making a DIY bike rack in the cargo area of my 06 KJ. I want to use the existing bolt holes that the cargo hooks use, but I’m not sure they are even bolts, seems like a giant rivet. Mine are so rusted that I had to hammer in an Allen wrench to get it to turn, but they just spin in place, so is it even a threaded bolt?
Attached photos of the hooks I’m talking about as well as a similar bike rack thing.
If these aren’t threaded I guess I’ll make some kind of clamp onto the plastic hook.
Anyone know if these are threaded, or if there are some hidden holes under the carpet or something?

 

[Gyro]

They are rivets.

Gyro

 

[joooooooooop]

Anyone know what the floor looks like under the carpet? Maybe there’s some other holes I can use

 

[KJowner]

The fuel tank is just below the floor so don't go drilling any holes!

 

[mike]

Is the steel thick enough to tap? Mayhaps you could use rivnuts?

 

[KJowner]

I've got a hitch bike rack, leaves the back empty for my dogs.

 

[joooooooooop]

Clamped some unistrut to the hooks, feels pretty secure, no drilling needed.

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