You could just change the incandescent bulb for a ceramic heating bulb like this: Ceramic Heat Bulbs for Reptile for sale | Shop with Afterpay | eBay
Probably much more efficient too as no power wasted to lighting the inside of your chamber for no reason.
That's not a bad idea, i'll have a look into it, i have to rewire the light as its a bayonet fitting and most of these are Edison screw.