You might consider a cable from the bike frame to your ladder as a safety should your bike rack fail.
I had a similar rack for several years, it too was on a 48-inch extension. I hit a bridge/asphalt joint and the whipping action ripped the bottom of the tube off. Two bikes and most of the rack were tumbling down the highway at 65 MPH in 5 PM in work area traffic. Fortunately, they hit no vehicles, went to the side of the road and no car crashes. By the time I found an exit and got back, no bikes and traffic was moving normally. It could have been a major disaster. I now have a different type rack, with less weight up high. The bikes also have the cable so if the rack fails, the bike will stay with the TC, and not bounce down the road. The cable is not tight, so there is some movement with the bikes.
Wayne