Two women, one bike= possible?

[Ktachapman]

Hi all,
My friend (also a girl) and I are planning a year long motorcycle trip a few years from now through Central and South America. Taking only one bike would be loads cheaper and in ways safer (one bike to buy, one set of parts/tools, one shipment between continents, one gas tank, one to park, and if we had two bikes and one broke it takes two to push so we would be screwed) but we have heard from a female with motorcycle experience that one would be impossible. We are currently both inexperienced and have not attempted to take the other pillion yet, but would appreciate the advice early in the game. We have the time to build strength if that is the main issue.
Related issues: - We are fairly short. I am 5'4" and she is 5'2".
- We will pack light, but a year is a year and our bike/s will be loaded.
- Our trip includes some time offroads
- Stopping every time it rained would be inconvenient.
There are lots of questions within this! Any advice or stories you can add to the discussion would be much appreciated.

Thanks, Katia