There are no hotels close to EZE. Not sure how much luggage you have but at the Retiro bus station they do have lockers for luggage, that might be one solution. This is a link to their web site http://www.tebasa.com.ar/

Seems you would have plenty of time to drop your luggage, have a nice vino tinto, a great dinner grab your bags and a taxi or remise and head for EZE at midnight.
Sam