Fitted a rear mudguard this weekend.
Purchased from a trailer spares supplier.
Used a 2 inch block on top of the tyre to provide clearance (as recommended elsewehere on this forum) and mounted as follows:
Front : screwed a block of wood to the new mudguard and to the top of the existing alloy guard. Bolting in a piece of alluminium box section would have been nice instead of the block of wood but it should do the job.
Rear : After making four different prototypes using the materials I had to hand I ended up with an alloy tube screwed to the rear body frame.
As many others have done this system has the front of the mudguard moving with the suspension and the rear fixed. Intuitively this seems wrong but looks like it will work. The front doesn't move very much and the movement is absorbed by the flex in the original alloy guard and the new plastic one.
Time will tell if the 2 inch guideline clearance is sufficient.