Percona XtraDB cluster backup solution
If you are bothered by being down to essentially one node during an SST, then make it a 4-node cluster.

If you are worried about the heavy disk I/O, well, you have not avoided that -- the restore will be heavy I/O.

If you think you can always avoid SST by trying to trick it into IST, you will probably be mistaken.  Galera sometimes does SST when you thing it should be able to do IST.