I am leaning toward bush beans over pole beans because of the labour/materials for trellising. If the limit is space rather than labour and materials, then pole beans are great.
Hay/straw mulching around the plants probably helps some with preventing mould on pods, and definitely helps keep them from being muddy.
There are bush varieties that are determinate enough to harvest the whole plant at once as others have described.
However, ones I've worked with are usually not so determinate that you want to leave them in the field until every pod is dry (unless your weather is really dry). If you leave them, the early pods will probably shatter or mould.
So, it works well to cut them just before they start doing that and dry the plants until the pods are all crackly.
For harvesting whole plants, a sharp sickle does a good job and I find it ergonomic enough. Cutting rather than pulling keeps dirt clods out of the final crop. Perhaps a scythe would work, allowing you to harvest standing. But the stems can get hefty. I haven't tried it.
If you do not have enough indoor drying space, outdoor drying racks are a possibility. Variations on this theme were widespread in northern Europe for a bunch of different crops. I have relatively little experience with this idea, but in some experiments it seemed to come through rains no problem - as long as there was sun soon, they just dried out again without molding.
The horizontal poles just sit loose on the pegs, so you start at the bottom, make a layer on the first pole, add the next pole and layer, etc. Some variations have a small roof.
For threshing, trampling on whole plants seems pretty efficient in my experience. It's a lot faster than picking off the pods. And very low tech!
An alternate I'd offer to the bike thresher design is
this treadle thresher. It is more compact, lighter, lower-tech, easier for a single person to use, and maybe clogs a bit less if you are putting through stemmy crops. Probably less ergonomic, but I've found it okay.
It would be easiest to use this thresher with picked dry pods. I think it would be tricky to feed it whole bean plants, but with the right variety it'd probably do fine. It works well with soybeans, but they have stiffer stems.
One other thought, since it's come up a bit:
Most "dry beans" are Phaseolus vulgaris. Mostly self-pollinated.
Runner beans are a different species: Phaseolus coccineus. These have the option of being insect/bird pollinated, so if you're trying to maintain multiple varieties it's a lot trickier to keep them seperate.
