If you give up the idea of a turning plow then what Carey has will fit your needs. That 2210 will be similar and its Powershift is a huge advantage. For what you describe I don't see a reason to go wider and longer, that just makes turning in tight spaces more difficult.
All of these 20~30 hp Yanmars are designed, optimized, to push maximum hp to a relatively big rototiller. (and incidentally, are optimized for a big rotary mower). They don't have the native weight to give traction and pull a heavy ground engaging implement - plow etc. An old International or even an 8N are a lot heavier and were designed for that, it's a different 'personality'. You could ballast a Yanmar to get closer to that weight. But my experience with the yM240 (YM2000) was I could feel the weight slowing down uphill climbs in my orchard when I had my oversize rear tires fully loaded with water. I had to stop and shift a lot sooner. After I put the ROPS on it I was less concerned with a rollover so I reduced the water ballast, regaining noticeable performance.
A 54 inch Yanmar rototiller and a 5 ft rotary mower will work well on a 2210. I don't see a reason to pay more for a larger tractor, in the application you describe.
If you do decide on the larger 3-cylinder instead, those are smoother and quieter. If you test drive some alternatives at Fredricks you might decide that is an advantage worth paying more for. The 2000 and 2210 do make quite a racket - I call it the sound of raw power.

... and I prefer to use my YM186D instead when it will do the job equally well because I don't need hearing protection on that one.