2021 Silverado cap wiring

[VE4ADB]

Hey all

i recently got a A.R.E dcu contractor cap for the truck. The wiring for the 3rd brake light canopy side is 2 wires. simple. however.... finding how to actually wire it to the truck is a nightmare. I have searched but didn't find the answer. My truck is a 2021 Silverado CUSTOM 5.3 dbl cab 6'7 box. being the custom i have LED tails but none of that fancy extra cameras. i read there's a diode that can be installed but the instructions state NOT FOR LED TAILLIGHTS, i obviously want the 3rd brake to work as a 3rd brake only. The cops up here in Canada will stop you for any and everything so id like to get it working. Is the only way to get it to work actually by tapping into the trucks 3rd brake light line its self? there's got to be another way. If there's not would "omitting" the wire to the truck 3rd brake light and extending it to the cap cause any issues or truck freak outs? So the factory light no longer lights up between the cap and the box?