I always worry about keys when we go away in the Eriba. Ours is old enough to be one of the ones that can lock itself if the door slams (I have had that happen on a previous one - luckily having left the kitchen window open - and have a hidden key box now for similar emergencies). We try and keep a set of car keys and caravan keys on each of our persons, but it's so hard to stick to. Keyless car ownership would make that even harder! Luckily we won't be using our new keyless car to tow with and I recently bought (at great expense) a second key for our other car, which will be replacing my old Volvo as our new tow car.
Claire never lets me forget the time last year when I went to play golf with my brother-in-law and managed to lose the car key somewhere round the golf course. In my defence the zip had burst on my brand new golf bag, but it was still an utter pain to sort out (although I did find them after three walks round the whole course...).
At night we have always been careful to lock the car and put all the keys safely away in the 'van, but old age and medication are making me increasingly forgetful and I am paranoid that I will do something stupid with the keys and the locking/unlocking. I have always thought that Eribas weren't popular theft targets, however the contents, of course, most definitely are!