I took the test many years ago on an 80' Yamaha XS-850. They do make allow for larger bikes to make wider turns. My son, who got out of the army and passed the driving test last summer on a Buell 900cc bike was less that perfect, but passed.
+1 for taking the class if you can get into one. If its like most years, they are full through the fall and have long waiting lists. But the entry level course is still worth doing, IMHO.
If you do go on the 1200LT, be sure to practice a lot of one-up, slow speed maneuvers. The Ride Like A Pro V DVD (Jerry Palladino) has several slow speed weave practice drills that you can lay out in the lot of a closed up store or Sunday morning at the local high school parking lot, as long as its not graduation weekend. Small cones can be had cheaply in the sporting goods department at Wally World, Target, or most sporting goods stores - near the soccer gear.
As David Hough and others say, don't look where you don't want to go. If you look at the ground, you will tip. If you stare at the cones, you will hit them. Use peripheral vision. If you get used to running the LT slow with high RPM and "dipping" around the cones, you can with practice, make it through 12' apart cones. The payback for the practice will come in parking lots and big rides for years to come.