Sean.
Reading your route I see that you are planning to go all the way to Cartagena, the reality is that from Cartagena is quite difficult to find a boat to take you to Colon Panama, take note that you can fly your bikes from Medellín or Bogotá, I understand that you Hill like to go with the rules for a record as a secondary goal in your ride, the rule says that you have to pass the same meridian as Panama City.
I will be contacting people in cartagena for a possibility of a boat and the cargo company with rates and timing, the nice thing about air cargo is that you may loose one day in your trip, by boat is a bit longer due to the size, most riders take their bikes in sail boat and it takes at least 2 to 4 days to get to Panama.
If you have any questions let me know, this way I can help you setting your route and timing in Colombia, I will do my best to ride south and meet you at the border coming from Ecuador.
I have planty of experience in Peru, Ecuador and Colombia if you have any concerns on what route to take, roads change alot in latinamerica.
In case you need anything special this is my email: <!-- e --><a href="mailto:tibejara@gmail.com">tibejara@gmail.com</a><!-- e --> 

All the best.

Tiberio Jaramillo
Medellín,  Colombia