Wiring on my trailer.

Not being anywhere near an expert on this issue, I would still go with the heavier wire. The lighter electrical draw of L.E.D. lighting may require less demands on the wiring, but that wiring leads a pretty rough life. I would use the heavier wiring thinking about the durability of the wire, more than the electric flowing through it.

 

There are calculators online that will find you the correct wire size given the load and distance. On one of my motorcycles that I rebuilt I downsized the wires for leds, but the wire was less than 4' long and feeding a single little led cluster on each side. You're going to be going 50 something feet to bigger lights. I'm not an electrician by any means (I just wasted a half hour at the hardware store today trying to add a circuit breaker to my panel, didn't know there are a million varieties)

Here's one for marine wiring but it should put you in the ballpark:
http://circuitwizard.bluesea.com/#
If anything err on the side of too big a wire.