This post mirrors my old imgur post on transporting my 645N.
My old Rowi bag. While it fits it's not an ideal bag for such a big camera.
I've been looking for a while for a better bag now - but many quite obviously can't handle the 645, or are too expensive and not locally available to just give it a try. About a week ago I discovered the Active Sling I. Manfrotto seems to be phasing the Active Sling I out - I've seen it available in multiple places quite cheap, and got a new one for under 30 EUR. Cheap enough to just order it to see if it's usable with the 645 - worst case I'll have a fancy bag for my 35mm cameras.
I can just fit the 75mm lens.
It does have side pockets in just the right size for an 645 film holder, though.
Length of the Manfrotto bag pretty much exactly fits a 645z with the 45-85 FA lens. The compartment on the left is pretty much gone, and just usable for something like a thin filter or papers.
This configuration requires that the camera is in the bag with the grip facing downwards. While not ideal it's still easy to remove it on the lens, and provides some additional storage space.
The space is enough for the 2x teleconverter and the 75mm FA lens. Pretty much what I'd like to carry with me as 'reduced' gear. The 75mm lens weighs next to nothing, but is very useful in low light situations.
Having a small opening on the bottom half of the side would make accessing the lenses a bit easier. I think the new model of this bag does have this, though I'm not sure if it's on the right side for this kind of configuration.
The 645N has a bit more space, both to the front and the side.
The bag doesn't have big external compartments, but there's enough space near the lens for one film insert. I might stick some velcro to the insert cover to keep it in place - that should be a solution I can live with.
It's not the perfect bag for this use case - but a step up from my old one. I'll still play around to see if I can find a better compartment configuration, but with the limited space there aren't that many options. If you're looking for a bag now and can get one of them for cheap I'd recommend giving it a try.
Just after initially publishing this album I noticed the product photo with a smaller format camera standing on its lens - something that never occurred to me as it doesn't fit with any of the bags I own.
I just tried it, and to my big surprise it just barely fits. The camera is a tiny bit higher, but the bag is flexible enough to still mostly close. That'll make the space in the bag much more useful.
Here's the bag closed. It's visible that the zipper is hardly closing, and needs some force to fully close. The red padding can't lie on top of the camera anymore - but does support the side quite nicely.
The 645N in upright position. The eye piece sticks out more than on the 645z, while the rest is a tiny bit smaller. I couldn't close the bag with the viewfinder on the left, like I put the 645z in.
I assume with the regular eye piece this would be a bit easier.
Bonus picture: The 'living dangerous' no padding bag for just quickly taking the camera only.