Hi Billy
I had a similar situation in Normandy once, the last leg was a brutal 100 miler in a Catholic region on a Sunday i.e. no resupply points!
Kind of had to wing it in this case, but in hindsight I would suggest either 1) restocking everything the day before for the final leg or 2) carry high energy bars & gels for the final stage and restock water on the day before. You could even use a map to scope out any natural fresh water sources if you're feeling intrepid.
Good luck...
Cheers
Andy