Showing which battery feed is in use

Morning all! Just about to hardwire a dashcam in, and for flexibility I want to be able to change its power source between a switched live on my main battery and a permanent live on my leisure battery. Easily achieved by wiring in an SPDT on-on rocker to switch the feed. However I'd like some visual indication of when it's using the permanent feed. Illuminated SPDT switches don't seem to be a thing, so I thought to just add a panel-mounted LED - but have now reached the limit of my minimal wiring knowledge! How exactly would that be wired into the circuit so as to show me when the permanent feed is in use without screwing anything up? Is the example LED even suitable?

Get 2 diffent colour leds(you can get single bulb but 3 colours) and wire to each power source, depending on the colour will mean which battery is powering it

Thanks Phill, great idea re multicolour. Will investigate. Can I just check though that a single colour LED would literally just be wired to the same switch terminal as the leisure feed (rather than the feed coming via the LED if you see what I mean), as in my rubbish diagram below?

try https://docs.rs-online.com/8dce/0900766b8148d932.pdf