[antonye]

I know it sounds like a way off suggestion, but why not buy a new bracket, as that's the only bit you need? You don't need the hinge parts - just the bracket which screws into the seat.

Cost is about 3 quid from a dealer for the bit you need that screws into the seat...

Part number 8271 0861A "Bracket"

Failing that, why not just take it off your road seat unit and use that for the trackday?

Or am I missing something really obvious?