I guess that at the front you would need something like the Miniator center cap to clear the center nut.
Orange is my new black
Uprated stub axle with modern seals has a much bigger hub nut and no grease cap.
I got a dremel and trimmed the inside centre of the cap, on mine the plastic was thick enough to give clearance. There mustn't be any split pin projecting, so I cut off the excess with a hacksaw after using a punch to make sure it was well folded back in the slot.
Hope this helps