Here's an idea for a bite leader...
Just slip about 10" of clear plastic tubing over your leader before you tie/crimp your swivel on.
Something like this stuff...
Just make sure the size is a snug fit and glue in place at swivel end with something like Dac Tac.
I havn't tried it yet and obviously it wouldn't improve strength, but I'd imagine it would help out a bit with bite/abrassion resistance, plus it's a neat finish and cheap to buy.
I dont see why it wouldn't work for both singles and twisty's.
Cheers Rob