I encourage you to just go exploring. Most of the roads in this area have very little traffic. Some have quite poor road surface, although I think I read recently that the council were carrying out repairs. The only road I would avoid is the main A761, but here you have the excellent cyclepath right alongside anyway.
I tend to avoid going into Paisley on my rides, so my rides are generally east-west rather than north-south. Still, here's a couple that I have done in the past:
http://ridewithgps.com/routes/937509
http://ridewithgps.com/routes/348533
Also, be aware that your are somewhat limited by the existence of the rather expansive former armaments factory west of Bishopton, the limits of which are not really very clear on google maps.