Va. Code Ann. § 46.2-648.1

The Department may, upon request, register any tow dolly or converter gear as defined in § 46.2-1119. For the purpose of determining the applicable fee for any such registration, the tow dolly or converter gear shall be considered a trailer and the registration fee determined in accordance with § 46.2-694.1. The fee for reserved numbers or letters on license plates for any tow dolly or converter gear shall be determined in accordance with § 46.2-726.