If you are in the position where your seqno is -1, and you need to bootstrap that node, you can recovery the correct seqno by running:
Which will output the correct seqno plus it will update the grastate.dat file.
Since you are not really changing any data nor the schema, just the underlying row_format, seems like RSU would be better, and a lot less invasive.
You might also take each node out of the cluster while doing the ALTER, or at least remove the one node from the proxy's list. This should avoid letting queries hit the table.
I feel pretty sure that the table ...