It's about six of one and half dozen of the other. If you take the usual route, you have to cut off the actual Kokopeli trail way out on the flats - miles from Skull. The cutoff is perhaps a bit closer to the ranger station, but not by much. If it's rained recently (yeah, fat chance this time of year), coming from Cisco could be problematic because of the need to cross Cottonwood Wash.
Once you cut off the Kokopeli, you can bike your way back to the fenced boundary of the Wilderness Study Area and go downriver until you reach the Hades Overlook cutoff. Or you could go all the way out to Big Hole, then work your way back upstream to a place to overlook Skull.
The Hades Overlook route involves a two-track that eventually will take you to where you actually have a distant view of Skull. I've never come up from the Big Hole side, but perhaps some else will chime in on that.
There is a "shortcut" entry to the WSA on the ranger station side, but it's sort of hard to describe. About a mile from the hardtop road, there is an abandoned gate on the left of the Kokopeli, that leads off to an old abandoned building. Next to the building, a two track leads down and up a few hills, and you reach another entry point for the WSA, with a signboard. Follow that two track a couple of miles and you'll get to the Little Hole WSA gate. After that, you're on the same route that you'd be on if you had cut off the Kokopeli way out on the flats.
I'm not sure if the current Wilderness Study Area regulations allow the use of bikes. I know no motorized traffic is permitted behind the fence, but a call to Moab BLM could tell you if mechanized travel is also prohibited. It that's the case, it's a long hot hike from the gate in the fence to Skull.
Check with the rangers and go over their maps to firm up your thinking about how you want to go about this, and so they know you're out there. Good luck on putting your jaunt together.