The part of easy peasy with the bridges is locals building a private way into the park - the Xterra will use it from outside the aux gate to the exit near iron mt. it is a nice, beginner trail with a little climbing.
Yes there are many unsanctioned trails in the park - that is the only one the Xterra uses, and we've been using it for 5+ years. the race loop is submitted to the park. since the race pays the park, each car pays the park, and the race pays the park police OT, it kinda works out in everyone's favor.
I may take on that mud puddle at the start of red dot. (Also the stream crossing pump house (not the lake crossing pumphouse))
There is that "low bridge" and a couple other challenges, not horrible. seems like the stuff sitting on the ground is cleared.
Besides, the mt bikers do all the trail work there anyway. Can always take some initiative and do some maintenance.