Sounds like an adventure even if you did get lost! You should be able to get a o-map, but if there may be a park/trail map online you could print and run with. I've done that for a few parks around here. The sad thing is when you get lost with the trail map! They're just not as accurate as o-maps (or so I tell myself so I don't feel too silly).
See you this weekend!
I should be able to help you with some old Greenbelt maps, though venturing off trails can be a bit bloody in some places.