Lighting gauges: proper spot to splice into dash light power?

hey, guys. I’ve been poking around under the dash for a long time, trying to find a a good spot to splice into the dash light power for the new gauges and preferably doing so without disassembling the whole interior.

Where do you guys suggest splicing in?

Also, now that I’m running stuff off of relays, I am brining in a voltage gauge. Is the cigarette lighter power an acceptable le spot?

Thanks!!