I'm still confused why Morgan would try to make the exhaust in welded sections this long.
With the proper supports, clamps can be used and look good at the same time.
The muffler should have a clamp on header pipe and a clamp on tail pipe, not a one piece welded assembly.
Harley probably has more vibration on our touring bikes as the motor/transmission is rubber mounted and NOT the rubber mounting that the Morgan uses on the motor mounts. My motor at idle rocks front to back about 1/2" at idle and the exhaust is all clamped together and the rear muffler hangers are through sliding mounts to allow for this vibration.
This is not rocket science.