Super awesome mod! I don't think you can make a warranty claim on this one any more.
To the manufacturers, there is no such thing as a minor mod.
Please enlighten us on the model and capacity ratings of the original indoor units. The mod looks very straightforward and promising. These mini-split units are beginning to hit the second-hand market en force in America, mainly due to the tug of war between the old school installers and the new wave of products. Most "seasoned" installers see the ductless units as toys compared to a full split system. When service is required, the owners get sold out of their mini-split, no matter what is actually wrong...
There is next to zero data on stuff like this, so any measurements you could produce as to operating conditions and effectiveness would be more gold from your effort. As always, many of us will be inspired by your work. Other, similar endeavors will follow.