Miami and the dates sound good. It is not for sure, but there is a Canadian family riding three DRs heading home around the same time. I took the boat from Panama with them and randomly bumped into them the other day in El Calafate. Pending some decisions they have to make in the next few days they also want to share a container, bringing the total to 5 bikes. I'll keep you posted.
Regarding the shipping company, I have no ideas. When I get better internet I'll do some research, I'm sure there is some good info on the forums and what not.