For bikes like the SV with not a lot of adjustment ie only preload this is what I do.
I set the
bike sag so it about 10mm or there abouts. Seeing as the spring on the SV relatively speaking is soft, any thing between 5mm-10mm would suffice. Edge towards 10mm for solo and 5mm for pillion/large boned.
Then just ride the t*ts of the bike
Ben