LEDs use a very small amount of current, small nav lights use a little more but not that much. When you have a very small current flow you have very little voltage drop.
For both of these if running up a mast I use 18 awg to save weight. If you have powerfull spreader lights than you should go a little heavier.
Of course you could run out the lenght of wire and terminate it at your panel and try it to see if you are happy with the brightness before you install it.