For those times where you feel you can't trust your second strongest Banker, "The Fickle 5" may be a better option than "The Faithful 5". It requires you to lay out the fallback bet not only on the 3 support matches but also on the weaker of the 2 Bankers, resulting in 16 lines of bets with the same overall stake as you would have used for "The Faithful 5" (but with much less money laid out per line, of course).
The additional combinations required over and above those for "The Faithful 5" can be seen on the downloadable Exotic Betting spreadsheet. Overall you will win more often with this particular variant, but on average you will only win receive about 50% of what you would have won for the same line with "The Faithful 5" using the same overall stake amount.
With this bet, and laying out on the Draw as the fallback position for the second Banker and the 3 support matches, you will lose everything if (i) your prime Banker fails to achieve the Win or (ii) just 1 single Away Win crops up amongst the 4 non-prime matches. If you opt to bet on the Away Win as the alternative result, you will lose if (i) your prime Banker fails to achieve the Win or (ii) just 1 single Draw creeps in amongst the 4 non-prime matches.