First, high and low stops are adjusted to keep your chain from going passed the highest or lowest chainring/wheel. They have little to do with any adjustment in between or chain line settings.

Mid front and large Rear rub sounds more like a FD adjustment issue or its just the nature of the beast.
Some designs rub in this condition, some don't. You could adjust the FD so that you get less/no rub in this condition but then it may rub in the mid-front, small-rear combo. If its prone to rubbing, adjust it for the least rubbing on each end.

The fact is, there is probably a small Front-??? rear combo that is near the same gearing as the mid front-large-rear combo. So if you're going to be spending any length of time/distance "needing" this gearing ... plan to shift to the small front - ???? rear and not worry about the rubbing.