Has anyone installed an OEM hitch? I only need the hitch for a bike rack (I will not tow a trailer, so no need for electrical). My local dealer says MB requires full tow package installation. Parts are $1800 plus labor. They said I could purchase the OEM hitch alone for $359 but would have to install it myself. I'm wondering if the installation of OEM hitch is as easy as the Curt or Draw-tite (plus needing to cut bumper) or if OEM install is much more complicated.