When I travel with my 500, I also usually take a shorter tele (300/4, 400/5.6 or 100-400, depending on what I am doing), 2 bodies, 2TCs and a flash.
I used to pack it all in a Lowepro Photo Trekker, which - barring its weight - is one of the nicest, most robust bags in which to carry fragile camera gear. However, it is quite heavy and visually quite large as well, and has been targeted for weighing a few times just because of its size.
So now I have switched to a Think Tank Airport Ultralite. It is quite a bit smaller, but less padded and square shaped, so I can fit everything listed above - except 1 body - in it. The extra body, maybe a wideangle lens and my general travel paraphernalia (media player, binos, Macbook) all go into a small laptop-style bag or a National Geographic shoulder bag (my man-purse, as my wife has dubbed it).
Anything which is not fragile - battery, chargers, cables, etc. gets put in check-in, along with tripods, heads, etc.
As of right now, this is the most optimal travel - as in flying - setup for wildlife photography that I have found. The biggest advantage of the Ultralite is that it is so small... no one gives it a second glance. And the bag (or bags) dont contribute much to the overall weight.
My only complaint about the TT is that it doesnt have locking clips to hold the opening flap in place in case the zipper fails or isnt properly closed. I solved that by getting a simple locking cam-band at a travel shop - after packing, this wraps around the bag so that even if the zip fails, my gear doesnt come crashing out.
Vandit