Doug,
The crows foot spanners are 0.375 inch deep.
Might it might work with a 1/2 and full nut?
What size is the nut?
I've got all manner of spanners, some long, some short and might file one down provided it's not one of my favourite ones.
I used to be a TSSC member and now don't have a Triumph so I've joined the Forum only. When I had my Triumph I occasionally visited the Thames meetings but that would be about 3 years ago.
If you want me to lend a hand then I'll call the club and pass on my telephone number if they haven't got it already, then you can call them and get it.
Regards, Mick