Ok, I know there has been a lot of posts about trailer wiring on here, but I still have a couple questions. Buying a pull behind trailer that has a 4 pin plug but my 14 RT has the older round plug in. I don't want to change the bike wiring because I have a Spyder trailer I pull behind it that uses that plug, this will be a second trailer for our winter home. Is it as simple as just building a pigtail type cord converting from the round plug to the flat 4? Can these cords be bought somewhere already made? Do I need to be concerned about anything else? Thanks much!