Here is my Loka w/Large ICU filled with all I have:
There are two obvious differences between how I pack vs. how you want to pack: Viewfinder and lens not attached. I had them both attached for the first year I had this gear. It works fine in the Large ICU once you experiment with positioning everything. I preferred to position the assembled camera horizontally near the top so other heavy lenses wouldn't press on the viewfinder.
How you do this really depends on 1) how much you use a tripod and 2) the percent of time a specific lens is used.
If you are going to shoot handheld a lot, then you are on the right track. However, once on a tripod it all changes. If you think about it, the viewfinder is used for two things: determining what lens to use (the mask lines) and framing. It’s really not excellent at either job, so I haven’t carried mine for two years. Here’s how I work:
Find a scene and take the pack off. I then wander around with the Alpa iPhone app in order to find just the right spot, and to select a focal length if it is not obvious.
Set up the tripod to about the right spot. This is an important step because like Graham, I have a good case of the dropsies. I find the best place to mess around with the camera is when it is rock solid on the tripod so I don’t have to worry about holding it. You’ve got lens, adapter, caps, filters, release cable, sync cable… ugh.
I have 3, sometimes 4 lenses. It seemed to never work out that the lens I had on the camera from the last shot was the one I wanted for the next one. I use the 70 and 150 most, but it is pretty evenly split between the two. Without a “go to” lens, it is more work to have one already mounted on the camera. If you have a much-preferred focal length, then carrying it around attached makes wonderful sense, and the back is exposed to the elements much less often!
The thing is once you’ve got the camera on the tripod, the use of the viewfinder goes down even more. You will fine tune framing by test shots anyway because the viewfinder just isn’t that accurate. Also, one subtle change in my photography since using a tech camera has been leveling the camera. I shoot much more often now with the camera level. With a DSLR I never paid attention to that because you pretty much have to point the camera at what you want and to hell with perspective issues. But with a technical camera you can now shift your way to the right framing. Again making the viewfinder even less useful. Others may have figured out how to use their viewfinder more accurately, but I just use the digital back.
So that is why I don’t mount the lens or viewfinder while packed. As Guy pointed out, if at all possible before this trip go out in the woods for a shakedown in order to work out these personal decisions.