When I worked at Destinations, my main motorcycle was a 1975 Yamaha XS-650B. I also had a 1974 Norton 850 Commando, but it was not quite reliable enough to be the "main bike". It was more of a toy, while the old Yammie was a vehicle.
The Yamaha had a luggage rack on it. It was the old-style square-tube package carrier which sat over the rear fender, and it was sturdy enough (and attached solidly enough) to use as a handle to pick the rear of the bike up off of the ground.
At some point or another, I decided that I needed to be able to carry my bicycle on the motorbike. So, I took an old strap-on trunk rack and mounted it onto the package carrier. When I carried the bicycle on it, it sat tranverse to the bike, just as it would on the trunk of a car. I had to be careful to remember the bike was there, so that I wouldn't smack it on something on the way by.
I never had a problem related to carrying the bike. But, a driver in Parker did, one day.
I was on my way to Destinations, riding the the XS, and I had my Specialized M2 mountain bike on the bike rack. It was about 9:00 A.M., so the traffic was pretty heavy. I had seen a couple of drivers give me a double-take, as I went by, but I just ignored it. I had ridden the high-wheeler enough to be accustomed to the gawking of the hoi-polloi.
As I was passing the intersection of Lincoln Avenue and Parker Road, I saw a driver in he oncoming lane staring at me. He was still staring as I went by him. I assume that he was still staring when he rammed into the rear end of the stopped car in front of him.
I heard the impact, and looked in my mirror just in time to see the back of the car that the guy had rammed settling down onto the hood of the staring driver's car, after the impact. I just kept riding.
I wasn't sure what else to do, at that point.
I am thinking of getting a similar package rack for the Scrambler. I just hope it won't cause mayhem in the streets!