After much soul searching, Adriana decided that we should travel as far as possible by land. We originally intended to travel the whole way by land but the Canadian government issued a travel advisory to avoid crossing the US-Mexico border by land due to problems with Mexican drug cartels.
We decided to take the bus to Miami, fly from there to Cancun and back, and then the bus home. Subsequently we decided to return by train.
I didn't do the full calculations at the time but have done so now using calculators.