The kits are all garbage as far as I'm concerned.

Get yourself some 6 way trailer wiring. It'll be 6 individual wires with an outer sheath. Tough stuff, usually around $2-3 a foot. Get your lights, and a plug, and a pack of shrinkable butt connectors.

It'll cost more but it will last, unless you're like me have a habit of backing into things and breaking lights.