Years ago, being of the female human type, we added on to a log cabin, using Horizontal logs, because I felt lazy, not wanting to lift 20 foot logs. And short Lodgepole Pine fit nicely in my pickup truck. That, and I could get them on my firewood permit.. I did have to flatten the sill logs, with my chainsaw and a hatchet, it took awhile, but worked fine.. The corner logs were raised, and a top sill plate was spiked in... Then each log was toe nailed 3 ways on the bottom, and spiked into the top, by spiking down thru' the top sill plate.. If some were not close enough, I ran the chainsaw in between to shave off bumps.. Windows were easily framed.. Later I stuffed the cracks with insulation, with a screw driver, and over time bought quarter round and tacked that over the cracks, silconing any needed spots... I found it a great way to built if you have the right kind of logs. Or like Hermit said.. IF you can you could flatted the logs, as some old timers use to do on some of their regular log cabins... Tho' some had 6 inch gaps to allow for settling... (There's some old ones like that near me, what chinking jobs they used, 'cuz those old logs never settled... )
Tho' if dry logs are used, you'll have very little shrinking. I used dead standing trees... I did find, that if you get a log that has a tendance to rot, this method of building works great, because you can easily replace that log.
Would I do it again??? Yes, if I had Lodgepole Pine, but here we only have Ponderosa Pine, and it's not good to build with, unless it's boards... The sucker rod sounds like it would add to the strength, or could you use cable like they do on round roofs??? Happy building, and you are right Hermit, those are nice photos Hoop....