I haven't been to Elm Ridge, but 15 mins down the road is a tiny trail system called Tannersville-Hathaway. I did an enduro there 4 years ago and the trails were fun. Kinda small though. https://www.strava.com/activities/1919870586
I think the 2 key/must-do downhills are here. If you follow the loop you'll see that we did one of them (the southern most one on the map) twice. Just be warned that the red Strava line that stops goes into private land. Thus the stopping.
If you have more time than this I can add a tweak to give you 1 more downhill but then you're on the wrong side of the hill towards the end and you have to go up & over again. But this loop as-is should give you a good feel for the park.