This has been bugging me for awhile, but does Dan Swano have his guitar strings setup upside? Sort of like how Dick Dale has his guitar setup (who is also a lefty). As in, lowest string is where the high strings are, etc...
The bassplayer in my old band didn't own a bass in the beginning and used my bass.
So due to the fact that I play right handed (but I am a lefty) and that he plays lefty he used the bass with the strings upside down.
It was really strange in the beginning but he managed it really well (at that time we played some thrash like old school death metal).
Now he plays a normal lefthand Warwick with a normal string setup, but he has no problem with switching between a normal setup and an upside down setup.