If you really are a prize tight git consider doing what I have done in the past - that is to travel one way over the weekend of the Bol D'Or race (this year 15/16 September).
Originally, for 20+ years, all French Autoroutes were free for bikes from thursday morning to tuesday night (I think these are the limits). This was on the grounds of safety as the authorities preferred to keep the hundreds of thousands of motor cyclist spectators on the Autoroutes rather than going through towns and villages.
A year or two back this was reduced to just the southern Autoroutes south of Paris and Rheims.
I believe this was further restricted last year as the toll operating Companies decided keeping up their Revenue was more important than putting motorcyclists lives at risk on other roads.