I use one of those stick up led lights that has a sensor in it so that it comes on when I enter the bathroom. It uses very little power and it is mounted on the underside of the high level cupboard in my Lunar. It shines down towards the toilet so I can see where I am going! In the middle of the night I can't be doing with fussing about trying to find a light switch. I think the version I have was made by Phillips and cost about a fiver about 4 years ago.
------------- 'A sure cure for sea-sickness is to sit under a tree'
I am sure I have one of those led push on lights given to me by a very good neighbour of mine some years ago. If yu would like to send me your address I can pop it in the post to you.
Hopefully this may solve your problem until the children a tall enough to reach or you possibly buy a new van!
The PIRs used for burglar alarms are 12 volt but they only stay on for a few milliseconds so you would need a timer as well to keep it on longer.
The other problem is that the PIR will require power even when the light is off. You may be as well to fit an LED bulb in the toilet and just leave it on through the night.
I suspect a pull cord mounted to a caravan ceiling is a recipe for disaster, especially with little ones as they can sometimes be a little heavy handed and the caravan ceiling is not really strong enough to take much strain.
What about something like this mounted inside the fitting?
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