Corner Canyon is primarily private property & USFS Wilderness, as it has for the last 20+ years. Its approximate boundaries are: Anything lower than the "Upper Corner Canyon Road" are privately owned (future subdivisions, Temple, etc) and anything above the road is in the Lone Peak Wilderness area. The fact the Temple is going in has NOTHING to do with the enforcment of the area. In fact they have actually really slacked off on enforcment compared to the days of the Sherriff Hummer & Helicopters...
At one time there were several decent trails in the canyon, the Draper Ridge Road is a very steep, climb that can be seen from I-15, it can be accessed from two different trails. The other trail was the "Movie Road", which was the sight of an old war film. They cut the road up the hill-side and it literally ends at a cliff, really cool drive (when it was legit). I've spent many of days in the area, camping, hiking, wheeling, biking, etc... Too bad it is losing ground to homes.
They are correct when they say that just about everything is closed. However, the main road is a County Road, and it 100% legit to travel as long as the main gate is open. They do close the gate when they road could easily be damaged by vehicles, such as in the winter. At this time I don't beleive they ever shut it since there is all the new developments at the top. Even when the gate was closed, there were a dozen ways to get into the area, some more shady than others.
I have some cool maps of the trails in the canyon, as well as alot of GPS routes up there too. Both of the "drivable" trails are very poplular with hikers heading to Lone Peak, and you "could" shave off several hours of the trip if you were allowed to drive.
I hope you do get a ticket for violating the law. The mud bogs up Corner Canyon are PRIVATE PROPERTY and have been marked for well over 5 years (current generation of signs, I'm sure 100's have been destroyed). Don't hurt our casue by trying to renegade on someones personal property. There are NO implied or possible rights to those mudbogs...