I think you'll have trouble if they see you doing 45 mph in VA and don't have a tag. Saw this for VA on the moped wiki at mopedarmy.com :
No moped shall be driven on any highway or public vehicular area faster than 35 miles per hour. If you operate a moped faster than 35 miles per hour, Virginia law deems this to be operating a motorcycle, which requires you to title and register the moped as a motorcycle and obtain a motorcycle license. Operation of mopeds is prohibited on any Interstate Highway Component.