You should use a relay to handle the load. This is one of the simplest ways I've found to wire in a relay. Uses the least amount of wire. If you wire it to the battery, add a fuse. If you wire it at the under hood fuse box, an Add-a-circuit is super easy. Wiring the switch from 85 to ground is also the safest because if any of it shorts out, it just turns the lights on instead of blowing fuses or melting wire.
Online Wire Size Calculators & Tables to find out what gauge wire for the light bar. That's from battery to 30, 87 to the lights, and lights to ground. That part of the circuit should be as short as possible. Jumping from 30 to 86, 85 to the switch, and switch to ground can be thin because it draws very little current.
Boogey Lights Amperage Data examples of current draw for some LED strips.
I hope that makes sense.