Wow, now i'm kinda worried on how to do this. Do you think the better option is to mod the unit phisically or to mod the 3v power supply (I found that this should be the voltage needed) to power the fan?
Mounting the unit backward is easiest and doesn't require additional parts.
Modifying the fan to run from an external power source would eliminate any potential power issues, but a lot of people don't have problems using the stock solar panels, so why bother?
In your case I think it just depends on your preference and/or ability to make the modification. (Assuming you didn't source your 5n1 from Australia in the first place)