Based on the budget document, it will be considered part of the MSRP. Only if you get the Tow hitch after you purchase the car, then it will not be considered:
The MSRP cap will include all line items on the purchase or lease agreement which relate to the value of the vehicle itself (including but not limited to battery upgrades, autonomous upgrades, wheel and tire packages, audio, and infotainment system). The MSRP cap will not include maintenance or vehicle care packages, additional vehicle accessories (i.e. first aid kits, floor mats, cargo nets, etc.), destination and delivery charges, tax, registration fees, title fees, and documentation fees since these line items do not relate to the value of the vehicle itself, but rather to the logistics, care, and maintenance of the vehicle.