My solution to this on the prototype, long before I knew it to be the prototype, was to cut through the lower end of the right hand crash bar about one inch from where it is welded to the lower plate. A solid steel rod was then welded into the lower end of the upper part and was threaded internally, probably 3/8 BSF. This solid rod would slide into the remaining short piece of tube. A steel bolt could be inserted from behind the lower plate and screwed in to the inserted rod. A tapered washer ensured that the bolt head was at right angles to the line of the bolt and when the bolt was tightened up it pulled the upper part, plus spigot, into the short part. To remove the exhaust pipe one only had to undo the hexagon headed bolt and very slightly pull outwards the long upper part. The crash bar has never been tested by sliding down the road on it but it must be about as strong as before it was modified.