Excellent input. I am very interested in your idea and progress.
From the sounds of it I think you are addressing one major question I had with the idea of cutting in the field and transporting for processing. I am not sure that we will get to the point of having even 1/2 acre of any particular variety/crop so if those are the numbers you are working to and are going down the road of transporting the cut crop to process out of the field that interests me very much. Can you elaborate on your thought process on this?
The contraption in the video with the powered drum to do the threshing looks like it may be effective on a small scale. However, how does that sit with your numbers on the acreage/production over those acres? What are your transportation plans - both the fresh cut crop to where you process and the chaff post-processing? Do you have a thought process on how you are going to feed the crop through the threshing process at a volume that meets your estimated production?
So, full disclosure. I'm not a farmer and I'm not a fabricator, so don't laugh.

I'm a long time IT guy who spent some time on a friend's family farm in my younger days, with a strong DIY streak and a desire to be more self sufficient. I don't have any plans to sell grain, but am interested in experimenting with some of the heirloom grains as a way to reduce gluten intake. My daughter is gluten intolerant, which got me interested in this.
Here's a short video of the thresher as it currently sits and the theory of operation.
I still need to add some baffles for air flow and I need to fabricate some kind of bracket for mounting the motor inside the back open area. I'm going to try this with a 1/2 HP motor that I have sitting on the shelf. If that isn't powerful enough, I'll swap it out for a 1 HP model. I did some basic CAD drawings for dimensioning purposes, but don't have a material list to go with it. If it looks like something you're interested in, I'm happy to share.
As for your questions about the logistics, I'm not certain what to expect. The machine is pretty heavy, but adding some wheels would make it easier to move around in the shop, which is where I plan to do my threshing. It will have to be hand fed, so it will still be a slower process than a combine, but a lot faster than trying to do it by hand. My goal is to have a two stage solution for threshing and winnowing. I know it won't be perfect, but hopefully, it's good enough.
As for portability, I suppose that I could mount it on a pallet and move it out to the field and use a generator to power it. I hadn't really thought about that.