topics in Fluid tagged with style sheets

I have 4 Fluid SSBs. Most of them use a custom style sheet that blocks ads, make Google Reader more readable, etc. Is there a way to have the Fluid SSB reference a style sheet that does not exist within the .app directory? Maybe have the SSB reference its custom style sheet in /Users/username/Application Support/Fluid/SSB. The justification here is that every time I update Fluid, I have to "View package contents" and replace "default.css." Is there an easier way to do this? Thanks.