Well you just need one at the bottom of the list pointing somewhere else, for the very rare occasion when this happens.
In reality it's never more than a few minutes outage when I restart the backend - but if you want to have the miner always going even when this happens, then yeah you need another pool at the bottom of the list in your miner web page.

Since it's always quite a short outage, your best bet would be to use a PPS pool as your final failover.
This way you get rewarded for all shares you submit, even if it is lower than you'd expect at a non-PPS pool, and since it is very short, your guaranteed to still be rewarded for that short period of time.