Update - Took a second look at the toolbox through the lens of just a bolt attachment, then took another look at the rack mountings. Realised that all I needed was a right angle, and I could hang the light off one of the bolts going through the bed of the rack.
Never throw away the mudguard mounting spares, that's all I'm saying.
Sorry - dark photos that I can't be bothered to edit this moment.
Update - Took a second look at the toolbox through the lens of just a bolt attachment, then took another look at the rack mountings. Realised that all I needed was a right angle, and I could hang the light off one of the bolts going through the bed of the rack.
Never throw away the mudguard mounting spares, that's all I'm saying.
Sorry - dark photos that I can't be bothered to edit this moment.