Mowermech is correct, you can wire it up anyway that you want, as long as all the lights work. But......If you plan to get a new trailer, plan to get a new truck or ever imagine towing a friend's trailer it is far easier to wire them up by the standards.
This happened to me and it was a real pain. I had a trailer that "worked" but then I purchased a new trailer and I had them both for a short time. It was almost impossible to tow them. And, one time I camped with a friend who had a boat that he towed behind a MH. At the lake we would drag the boat to the lake with my truck. Guess what? What a mess. I will never do that again.