Here's what NH says about my EZ Pass account:
<dt style="margin: 10px 30px 5px; cursor: pointer; font-family: Verdana, Arial, Helvetica, sans-serif; padding: 0px 6px 5px; color: rgb(64, 64, 64); font-weight: bold; position: relative; top: 10px; font-size: 11px; line-height: 15px;">I sometimes pull a camper or trailer with my vehicle. Can I still use my transponder?</dt><dd style="margin: 5px 50px 10px; font-family: Verdana, Arial, Helvetica, sans-serif; padding: 2px 9px; color: rgb(0, 0, 0); position: relative; top: 10px; font-size: 11px; line-height: 15px;">Yes. In this instance the equipment in the lane is designed to identify that your vehicle is pulling a trailer and you will be charged accordingly. However, if you think this will be a regular occurrence, you should call the Customer Service Center and have them send you a transponder programmed for the vehicle classification you use most frequently. You should never use your transponder in a vehicle type other than the one you initially requested (i.e. car transponder in a tractor-trailer).</dd>