I think you will be fine taking film (400 ASA) on the airlines particularily 120 as it is not metallic under the xray.
I would suggest one format though, with a backup body.
I totally sympathize with the larger negative of the 120, and if you can take a 250mm or better yet a 500mm (or a 2x tele adaptor) you will be able to crop to what would have been a 35mm neg anyways.
Bean bag on the roof of the car. or put Arca swiss type plates on your cameras and long lenses with a quick release plate on The Pod
http://www.thepod.ca/
I emptied out the supplied filling and filled with lentils and left them in Africa and put the stuffing back in when I got home.
Don't worry able film changes; you don't need 200 shots of the sleeping cheetah.
Timing and country is wrong but
http://www.infocustravel.com/
In june is inexpensive, Photographically oriented and popular with females numerically.