I would use some oil diapers to absorb the oil then dispose of the remaining water overboard or by pouring it out on some asphalt.
In MD, as in VA, that will likely result in some upset people and possible fines.
By both state dept of environmental quality...that contaminated bilge water and subsequent rinse water will have to be dealt with in a correct fashion. That means that you will have to pump it out...to a barrel and have it disposed of properly.
Ignorance is no excuse to break the law. Your yard will have the appropriate stuff to deal with this. It will cost you..about $1-2 per gallon, a year ago when I last did this.