Extending sink drain rough in. Legal? Correct?
I believe the 22 inches would just be a maximum height you could have it in order to achieve the  proper slope for drainage.  It is not uncommon to plumb sinks into drains that are less than 22 inches .  Just use a longer tailpiece or extension from the drain basket down to the trap and then over to the drain.  Your wife's husband can rest asured that it will be all right.