Unfortunately you won't be able to go over Garden Canyon Road like you were hoping, it is locked off by Fort Huachuca. Another option is to go over Montezuma Pass via Coronado Memorial Raod off HWY92, then west on Montezuma Canyon road . That is a pretty cool ride up and over the mountain and across the San Rafael Valley. If you stop just past the Coronado National Memorial Visitor's Center, there is a short hike (.5 mi) up to a cave that you can go down into that is pretty cool, just bring some flashlights. That road will take you all the way over to Nogales if your interested also. Any problems and just wave down one of the friendly BP vehicles along the way and they can point you to some more interesting places close by.