The main compartment with the accessory bag in place has the allowance for an 11 inch lens attached to the 5dm2, if you remove the grey accessory bag this increases to about 14 inches.
In this picture,
1) You can see the spot for the 430ex
2) The 400mm DO will need to fit in where the 24-105mm and the 135mm f/2 are, need to remove the divider
3) Your 24-105mm will need to go where the 200mm f/2.8 is, no issues here.
4) The 24-105mm hood can go where the TC's are or where the Point and shoot camera is .
How everything fits will depend on the width of the 400mm DO, length should not be a problem.

I am glad to see I am not the only one who carries around a Panasonic Lumex around in my bag
I carry my DMC-TZ4




