While the final product doesn't display the degree of disagreement, my adversarial collaboration with /u/mpershan remains by far my best long-form dialogue in the vein you describe. Even there, I don't know that our views were precisely as disparate as you're hoping, but we sharply disagreed on a few dozen related topics and spent more than a hundred hours, best as I can account, working across the various folds of our disagreement.
He and I share our experiences with it here. I'll quote the most relevant parts:
My adversarial collaboration was similar to how [researcher Daniel Kahneman] describes his experience [in his own adversarial collaboration]: a “failure to disagree.” When Michael and I zoomed into an issue at the object level, we usually agreed. Then we’d zoom out and realize we used that object-level detail as part of two drastically different narratives. ...
I grew to trust experts more as I noticed that when you dug deep enough, most of the serious researchers came to pretty similar conclusions but wrapped them in different narratives, and really bad ideas that filtered through were less because the serious researchers had really bad ideas, more because their messages got distorted or ignored to better fit political agendas and the vagaries of people’s opinions. ...
That happened again and again–where I would see an unusual, academically intensive approach that got good results, we’d talk about it, and he’d ask, “right, but what’s the point?” Sorting by aptitude over age level, high-intensity accelerated math programs, early (pre-K) academics, so forth. It’s worth repeating–we almost never disagreed about what studies showed, just on the importance of particular studies and particular points. And that was enough to fuel a hundred pages or so of disagreement. ...
First off, it can only work if both are very, very willing to talk about the topic–the whole topic, not only their pet issues within it. If you find yourself uninterested in a part of the topic the other person is passionate about, pay close attention, since that’s often the most important part of disagreement. Second, it takes a lot of time. We took more time than strictly needed because we both enjoyed the research and conversations, but I’d guess 50-100 hours is a reasonable amount of time to set aside. Third–expect to find a lot of disagreements that boil down to differing priorities and interpretations of object-level facts you both agree on. If you’re both reasonable and willing to work together, you may find little factual ground you disagree on, even while telling two very different stories of the big picture.
I don't think a few hours is sufficient to really dig into a disagreement that large-scale. This is largely because of your last bullet point—a lot of those tiny points spiral and expand and are worth discussing, and if you want to address the whole disagreement, you need to drill into tiny point after tiny point after tiny point to get there. That's one of your failure states I disagree is actually a failure state, with the other being:
We would talk past each other on basic points, since we just have different starting points and values. For example, they might make some point about income inequality under capitalism, which I see as irrelevant since I don't care that much about income inequality. And I might make some point about material prosperity under socialism, which they would see as irrelevant since they don't care that much about material prosperity.
This is essential, and you see me alluding to it in my quoted portion above. You will talk past each other. Constantly. And then you can zoom in and notice how and why you're talking past each other, precisely which differences in values inspire that. It's fascinating. Again and again, with an honest opponent and being honest yourself, you'll notice the feeling of "Well, that's probably true, but... I don't care about that."
In terms of not knowing the basics of the others' field, well, that's one reason it takes so long in my estimation. You need to be prepared to do a lot of serious reading if you want to properly disagree with someone, because you're not really disagreeing with them, you're disagreeing with the set of ideas they've absorbed and assimilated into something of a unified structure. To address that, you need to dive into not just what they say, but what the people who convinced them say. I don't think there's any real way around this.
Anyway, the short of this all is: It's possible. I don't think an in-person debate is really the right way to do it at all. Too short, too performative. It takes a long time, serious effort, and mutual trust to do it right. You can also learn a ton and develop your own views to much greater depth, even if you're unlikely to ultimately shift them that far because most real disagreements are values-based, not fact-based.
That's my experience, anyway.