Motorhome key safety

Hi,

This summer for the 1st time we're doing a 3 week tour of France. We've tried to cover all eventualities to ensure we have a great time. But one concern we do have is the trouble it would cause if we were to lose our MH key leaving us stranded. We've never lost a car key etc before but it could happen.

I was thinking of hiding a spare key on the MH perhaps in the toilet cassette locker and when we go out not locking that locker. There is a small area in the cassette locker where a key could be reasonable hidden. Another idea we've had is to leave a key with our neighbour and ring them to courier it to us in the eventuality of a key loss. 

What have you done? What do you think of our toilet cassette idea?