As Ken said Ira will most likely chime in with sage advice, that said It's up to you to prove you rode the ride. photographic evidence may help if it were me and I couldn't fix the bike I'd zero the odometer your using at the start get a photo that shows your bike and the pump with fuel dispensed visible and a corresponding photo of the receipt and phone odometer. Do the same at each stop. Explain why your outside the norm in your application.
I think I would be more comfortable using a dedicated GPS rather the a phone but each could have issues if you travel with it off.