we are constantly advised when planning a transit of controlled airspace to have a plan b if rejected.  I'm in the low and slow fraternity so most of my flying is fairly local and I can manage to hand fly around airspace if needed.  Would be more of a problem if this happened in unfamiliar territory.  Is there a plan b facility I am missing?  If not could one be created in the original flight planning ?  Say from the airspace entry point on the plan a.

Might save a few infringements!