Use the Puma Heated Seat switch
YUF500150LNF (around a fiver

), and swap the heated seat switch cap for one off of a switch blank.
You can drill a 2.5mm hole in the blank cover, so that the Orange 'tell-tale' LED can be used to indicate when the switch is 'on'.
Have a look here -
Land Rover Owner • View topic - Def >2004 Dash Switches without graphics
If you're good with an engraving tool, you can engrave your own legend on to the blank cover.
YUF500150LNF is a live-switching, latching on/off switch, unlike most of the other switches that either switch the earth, or are momentary switches.
It uses the Black 5-way switch connector, which I sell on eBay, see link in my signature.
It's wired, as follows -
Pin 1 - Live in from fused supply
Pin 2 - Dash illumination
Pin 3 - Not used (but is internally connected to Pin 5 - Earth)
Pin 4 - Switched live out to accessory
Pin 5 - Earth
.