Looks good jez, feel free to bang up another hitch
For the hitch locking could you have the lock on the backside of the hitch, locking mounts run under the hitch and drop 2 small pins down the back, Get what i mean?
For the JCB, looks realy good but how hard is it to run the aux pipes along the Inside of the stay bar for the offset, save them dangling down when your working offset, thats where the real ones have the aux pipes
For buckets Try Udimore, im sure he had some not long ago