1. Obviously a front wheel chock!
2. Soft ties (one each side) around the lower triple tree plate. Ratchet straps to these soft ties to some anchor points forward of and somewhat outboard of the tree plate. Yes, you should compress the forks but, no more than 2"s!
3. On the 1800's the best tie-down points to stabilize the rear of the bike is the frame, under the side covers. Soft-ties around the frame and ratchet straps to points that are outboard of and rearward of the point where the soft-straps are wrapped around the frame. These should just be snug with no real "force" applied.
Front straps should be attached first to insure the bike is "pulled" into the front wheel chock.
A condor(or similar)wheel chick that "stands" the bike up is a excellent choice. However, if you have a front fender extension, make sure you have clearance to the wheel chock!
Check the straps often while towing! Have a extra handy, just in case!