Front derailleurs are sized both for the large chainring but also by the teeth difference between the large and middle rings. If the difference is not enough you will run into your situation, where the derailleur will need to be set too high for the large ring to avoid hitting the middle one. The curve of the derailleur cage may also not be ideal for the large ring. You may find that shifting to/from the large ring is not ideal but usable. Or failing that a different derailleur may be required.