Yeah I suppose it would be easy to cheat on that one.
I'd say posts without showing an ending date in a certain time , and ending mileage would be void. For example: before you head out take a video of the date on your phone or maybe a billboard somewhere as well as your starting mileage. Then you can say approx how long the trip will be, wether is be days or hours. At then end, take a video of your ending date and mileage in the same way, as well as a GPS route you took. There are many apps out there that leave a GPS trail of your journeys.