2 Hitch Converter

So I just got a hitch installed, and I need to wire it up. I'm trying to do it in the least expensive way possible. I went and bought a standard 4 plug connector kit, thinking I could just splice the one wire to ground, other to a brake line, and the others to the 2 turn signals.

However I was just cruising online trying to find a wiring schematic, and I ran across a site that made me think that maybe its not that easy. It says if your turn signals are seperate than your brakes, then you need a taillight converter. Also I see alot of them want to be hardwired into the battery. Seems as if splicing into the tail lights might draw too much voltage.

So is my original plan to just splice those 4 wires a bad idea?
What's the cheapest and easiest way to wire up my trailer hitch?