Regarding these rear donut hangers, I suspect that I am using the wrong ones which stretch a bit too much and allow too much play in the exhaust.

I have been using the basic donut shaped ones, which do not have the cross-section in them. I think that allows the exhaust system to ride a bit lower than it should. When installed, the exhaust has about 2 inches of side-to-side play available. It also rides about 1 1/2 inches below the upper rubber stop.

Should I be using a shorter donut, or the one with the rubber cross-section?

Please advise. Thanks.