It doesn't hurt to let the motor clubs know that you exist, but never sign a contract with any of them. If you do, you will be locked into whatever discounted rate you signed on for. It is much easier to get into a contract than it will be to ever negotiate a rate increase. They may not call often, but when they do, if you quote your commercial rate and make them pay in advance with a credit card, then you make a profit on that call, just like any other call. Keep in mind that they won't accept your price if they can find another tower to do it cheaper. Don't be that guy!