So on to 'the hop'...
I suspected the LF, so swapped the spare to that corner first.
Test drove around the block.
No change.
Reinstalled original tire to the LF.
Swapped spare to RF.
Test drove around the block.
No change.
To reduce the physical effort and still retain the point of the task, I installed the original RF to the RR*.
*If there was no change when running the spare on either front corner, I determined that all 3 of those were "close enough" to each other that I didn't have to include an extra swap just to look at the RR.
Test drove around the block.
Noticeable improvement.
RR does not appear to show any evidence of damage, out-of-round, bulges, etc. It looks like a normal tire.
Next step is taking it in for a rebalance to see if maybe it's thrown a weight.
I already tried to get all of them done while I waited at a local shop, but they were booked.
By doing just the one (RR), I can drop it off tomorrow morning and still drive the Jeep to work.