If that's Janes Island MD I would suggest not trying to get in your site that late. There is heavy tree canopy in most of the park (dark) and with that big a unit combined with the trees in the wrong places it could be a stressful event. A gasser with headlights off may not disturb but an older diesel may get you some feedback that late.
There is a large parking lot by the boat ramp where you could spend the night or leave the rig and walk the site so you know what you're up against.
BRING LOTS OF BUG SPRAY! Have a good time and get some crabs in Crisfield while you're there.