I would not go that route. Buy the more efficient units made in 208/240, and power them accordingly. Personally, I would not try this with a 3k unit, I'd go at least 5k, there isn't that much difference in price. Try to buy an inverter that has split phase natively so you don't need an auto-transformer.
Also, having used MANY mini splits in projects, I always recommend that people buy the smallest unit they can get for the load, and buy separates. Not the combined multi head unit. Those are much less efficient. 22 Seer for a mini split is lousy by today's' standards. Separates cost more, and cost more to install, but you get what you pay for. Also, long term they will save you a lot of money. I wouldn't even look at units under 30 SEER.
Knowing nothing about your layout, I might add that in our projects, we have often found that a single unit will cool a much larger area than you might supposed. In your scenario, I might think about 2 single head units, around 33-36 seer, and see how it works.
When I put them in, I do all the mounting, conduit, electrical runs, breakers, etc. Then I call an HVAC technician and have them purge the lines and do the coolant.
Good luck!