Use these to throw a strap thro and ratchet tight to keep ■■■■ tight to the headboard. Ad you can see they’ve seen better day’s. Dunno what they’re proper name is hence can’t find them on googley woogley.
Ah the…
‘Tilt your head at 90 degrees strap’. 
I Googly Wooglied and couldn’t find anything similar.
I suggest contacting the trailer maufacturer and seeing if they have them in stock, what ever they’re called.
We use similar straps they’re only 1 tonne and I think they are from Tiger Trailers!!