I just did something similar when I installed a victory 4x4 rear bumper which has 2x 3" led lights in it.

I tapped into reverse light on passenger side (from cargo area) using t-tap connector, relay and aob switch.


Standard relay connections:

85 to aob switch
86 ground
30 positive wire to led lights
87 accessory-on power (run with add a fuse to fuse block down passenger kick panels)
87a wire from reverse light

lights come on when put in reverse like normal, And, come on or when the switch is used in dash.

Check this out at Amazon
LED Light Push Button Switch with Connector Wire Blue Backlit Kit Compatible with Toyota Tundra Tacoma 4Runner-Rear Light Symbol Amazon.com: LED Light Push Button Switch with Connector Wire Blue Backlit Kit Compatible with Toyota Tundra Tacoma 4Runner-Rear Light Symbol: Automotive


Amazon.com: ONLINE LED STORE 6 Pack Bosch Style 5-Pin 12V Relay Kit [Interlocking Harness Socket Holder] [14 AWG Hot Wires] [SPDT] [30/40 Amp] 12 Volt Automotive Relays for Auto Fan Cars: Automotive

Qibaok 240 PCS T-Tap Wire Connectors Self-Stripping Quick Splice Electrical Terminals and Nylon Insulated Male Quick Disconnect Spade Terminals Kit: Amazon.com: Industrial & Scientific

Amazon.com: Uriveusa 12V Car Add-A-Circuit Fuse TAP Adapter Fuse Holder with 10A, 20A Fuse [Upgraded Fuses] - (2 Pack) (Mini Fuse): Automotive