There’s quite a few trails visible on both sides of the 73 while heading south through the Newport/Laguna area.
Here’s a general description of what you can typically see while heading South on the 73 around the toll plaza / El Toro exit area.
On the right side, Bommer Ridge and the Upper Laurel Canyon are pretty visible, as well as a few of the non-authorized trails (Maries, Shredders, Lizards, and DS).
I believe you can also see the currently non-legal, but hopefully soon-to-be legal Corridor connector trail that connects Aliso-Woods to Laguna Coast.
On the left side a number of the trails in the City of Irvine Open Space Preserve South, and the Northern Section of the County Laguna Coast Wilderness Park trails are visible. The Irvine Open Space is accessed by Docent led tours only; and the Laguna Coast Wilderness Park on the North Side of the Fwy is in the process of being brought into public use. There’s a new nature center being built that should be completed shortly, but I’m not sure of the exact timing on the dawn to dusk access to the northern area.
There’s tons of legal riding out there, and the trails are well marked with the exception of one recently opened trail (Emerald Falls). If you are new to riding this area, just pick up a map at the front gate of the Wilderness Park which shows all the legal trails in Laguna Coast. The trails in El Moro have nice signs that show the trail map with the legal trails.
If you are unsure about the area; the basic rule which is mirrored pretty much in the other wilderness parks is that only the trails that have trail signs, and/or are shown on the parks authorized maps are legal to ride or hike.
Have fun out there and just watch for the trail signs so you know you’re on a legal trail. No sign = a non authorized trail.
Hope this helps.