Judging by the info I've looked at, the tour comes in from the east on Wednesday afternoon to Rouen, and heads back out east from Rouen on Thursday morning.
I'm coming down from Calais, and plan to use the A28 toll road that runs Calais - Rouen - Alencon - Le Mans, and costs about 40 euros in total tolls. At least it shouldn't be affected by the tour on either day.
I'll be flagging you all out at poste 106 (the marshals poste half mile after Arnage, on driver's left) so waves on green flag flags are obligatory, especially during the night races!!!!
So look out for the flying wheelchair, or the Big White Box with double checkers on front and rear. Me and my good lady will be aboard.