If there’s not enough room or indeed if you do not have the machinery to make that rather neat snail cam stop there another possibility. It’ll need a bit of elbow grease with a file if nothing else is available.
I can’t see anything wrong with making a filler to occupy the space in the slot not occupied by the bolt. This will mean measuring up the slot and everything associated with it as accurately as possible before assembly and then determining the position of the bolt relative to the ends of the slot when assembled and adjusted.
From the photographs a dimension taken from the O.D. of the washer to one end of the slot should locate the centre of the bolt if done carefully. (Hence the reason for measuring everything.) From the obtained dimensions it should then be a fairly simple job to first drill a suitable close fitting hole for the bolt in a scrap of material and then file it up to fit closely in the slot.
The only down side I can see is that any resetting will require another spacer to be made, on the up-side, (tongue-in-cheek), there is a small weight saving to be made for the racier minded owner, not that it is an issue for me as I probably weigh more than my bike anyway!
