Does or has anyone travel or know if it's possible to travel by commercial plane with the DJI S900? The current LIPOs are too large to be checked in and also do not qualify for carry on. I'm wondering if anyone has overcome this problem.

This is a problem that we are all going to face in the future with Lipo batteries, IMO your best best is to find a shipping company that will ship them to your destination before you leave.

You have to ship ahead.  Shipping has to be by commercial carrier since the postal service in the US will not ship large LiPos.  I am not aware of any legal way around this with batteries over 160Wh.
However you can bring a bunch of up 100 watt hour batteries so if you can deal with a bunch of 4500 6S batteries you can do it.