I just did mine today too. I used the Hopkins part#48895, from AutoZone, which will work with both LED and incandescent lighting. The way I did mine, I now have a pigtail in the rear for both 4-wire & 5-wire trailers. I like being versatile. Converter was $24.95.
The thing that will mess you up, is the bike harness colors are the same color, but different function.
Bike Harness next to battery...
Black=ground
Yellow=brake...This is where the red wire from the converter ties in.
Blue=tail/running light
Brown= Left Turn
Green=Right Turn