I just returned from two weeks of assignment work in Alaska, and as usual had a ton of gear with me. Lights for interiors, prime lenses for portraits, travel zooms…and of course the big 600mm F4 for wildlife. While the other gear fits nicely into rollers and backpacks, the 600mm is a beast. But one look at a distant puffin through that lens and carrying it around would be worth it.
The best way to travel with this lens, both on the trail and in the airport, is using the Tamrac Anvil Super 25. This pack is actually a backpack that can carry the lens on the trail and in the field. The Anvil 25 has a full suspension system, and carries very nicely. The case comes with a waterproof cover, so walking in the rain is not a problem. Better yet, the case is just big enough for me to carry my 600mm F4 with a D850 attached. Hiking to distant bird rookeries is no problem. Outside straps and buckles allow attaching a tripod as well.
There are other backpack cases out there, but this case allows you to remove the hip belt for travel through airports. I have put this case both in the overhead compartment and underneath my seat on commuter prop planes. When I get to my destination, I take attach the hip belt and I am ready to go. Very nice!