Might be an idea old-bean.
You could just wait and see if they burn-out though.
I guess the Xenons are rated at 12v DC.
None of mine have ever burnt out though, and we have about 17 Volts from a 100 Watt transformer at MRW.
Surges of power from throttleing, are just as likely to affect the bulbs as 'straight' over Voltage.
Imagine switching a ceiling bulb ON & OFF 'continuously' for a few hours...
...wouldn't last that long, probably.
You CAN run most bulbs at a higher Voltage than specified.
But combined with the 'Thermal Shock' of repeated dimming & lighting; they could end up producing as much light as those NASCAR headlamps !
If you get a soldering iron, you could make a simple 'constant lighting' setup for your cars.
It's perhaps a 'learning curve', but could be worth doing them as you go along, and the garages get bigger !
With LED's these circuits are fun, as the car headlights stay on for quite a while even after you take the car off the track !
If you ramp up your lecy-tech a bit you could put LED headlights, interior lights & working brake lights in the Aston old-chap.
If you fit the forward mounted .50 cal machine-guns as well; you might be able to do 'realistic muzzle flashes' with some micro LEDS !
That's what James Bond would do.
Or should I say 'Q'....