Scott,
Senkos don't float...they attract bass because of the way they "sink".
Out here in the Delta, color #208 is probably the most used but even that changes by personal preference. When the bass want that bait almost any color will work and work pretty good!
Just texas rig it weightless on a #3/0-#5/0 EWG gamakastsu hook (superline hooks work good also), skin hook the point, on the end of some florocarbon and cast/pitch it to some cover and the fish will eat it up! The size of the hook and line type will change the rate of fall and either improve your bites or turn the fish off...just trial and error there.
But remember one thing....buy plenty if you find one that works because the don't hold up to the punishment.
Tom