How do you deal with your big white lenses in the field???

[Joel Eade]

I use a Gitzo tripod with Wimberly gimbal head and carry it over my shoulder, making sure its all locked down tight. I have padded tripod leg covers on the upper section. When not using the tripod I carry the 500mm lens and body by the lens foot.

[HDNitehawk]

I use a Gitzo tripod with Wimberly gimbal head and carry it over my shoulder, making sure its all locked down tight. I have padded tripod leg covers on the upper section. When not using the tripod I carry the 500mm lens and body by the lens foot.

+1, but no padded legs.
I don't use a head on my monopod. I do the same with the monopod, balanced over the shoulder. Watch a few football games and you will see the photogs carrying their 500mm this way.
With the 500 what is more important to me is how I carry the 500 in my truck. I have a dedicated back pack for the 500, when in a park to have it at the ready I can open the bag and get it prepped and ready. I take a few of the wife's pillows to prop the bag up on the center console and I am ready with the lens and camera sitting in the open pack.

The 300 is a totally different animal. Using it is more like using an oversized 70-200mm.