Hello and welcome to the forum!
That’s exciting you’re getting into reenacting. What area of the country are you in? I don’t know specifically of a Washington Life Guard unit, though I am familiar with a larger group out in Arizona that might have more specific knowledge of where one might exist: http://www.georgewashingtonsarmy.com/
Might be worth a try contacting them to see if they know of any units (if you’re not near Arizona).