Only accessible on Irvine Ranch Conservancy Wilderness Access Days (it may or may not be in use on these days).
The West Loma Ridge Jeep Trail is a flowy doubletrack on the ridge. It can be accessed via Shoestring (if it's open) or Hicks Haul Road (paved). This route offers good views of the OC coast on a clear day as well as the Santa Ana and San Gabriel Mountains. Even though the trail continues beyond Shoestring, it was not open for use on the day I went.