Hi Harvey_S,
Paul and Randyman's advice is solid. The space behind the port is the least of your concerns. Surrounding or nearby surfaces (shelves, cabinetry, walls) can have profound effects on a speaker's sound. Thank heavens you nixed the notion of sticking them inside the base cabinet behind grille cloth (Ian would weep!).
Your plan to use the countertop or leave them on stands is the most desirable. You could do some A/B experiments, putting one speaker in a temporary location and the other M22ti elsewhere, switching between the two to see how much the sound changes. You may be surprised.
Regards,
