I'm Colby Martin, the director of the SEMA Action Network (SAN). We noticed your posting and wanted to offer some assistance. As you may already know, the SAN’s mission is to keep the automotive hobby free from unnecessarily burdensome laws and regulations at the state and federal levels. To follow is information that will answer your question. Additional research on Maryland bumper height regulations can be sent if you send us an e-mail: SAN@sema.org
You have correctly determined that whether your Jeep will be required to meet the 20 inch bumper height limit or the 28 inch bumper height limit depends on whether your Jeep is a Class A passenger vehicle (20" height limit) or a Class M multipurpose vehicle (28" height limit). Maryland defines a "passenger car" as "a motor vehicle, except a multipurpose passenger vehicle or motorcycle, designed for carrying 10 persons or less" and a "multipurpose passenger vehicle" as a vehicle "designed primarily for carrying persons and which is constructed on a truck chassis or with special features for occasional off-road operations" or a vehicle that "has 3 wheels" or a vehicle that "is of a unique design that does not clearly meet the requirements of any other class, as determined by the [MVA]."
Since your vehicle could have been legitimately titled and registered as a passenger vehicle (Class A) or a multipurpose vehicle (Class M), it all comes down to which class was specified when titling/registering the Jeep. If you or the dealer did not indicate that the class of the vehicle was "Class M" ("multipurpose") when first titling and registering the vehicle, it is likely that the MVA registered it as the default "passenger vehicle" and you will need to change your registration or be subject to the 20" bumper height limit.
As SAN members, thousands are already doing their part to heed the call and defend the future of this great pastime. Unfortunately, many more voices are needed in the battle. Please enlist in the SAN without fee or obligation at http://www.semaSAN.com
if you haven’t yet. You will never receive spam from us and we will keep your contact information confidential. I look forward to counting you among this growing force!