Be cautious that you inner cover doesn't sag. This can imped traffic to the sugar. A sagging IC could also funnel dampness to the hive center and cause it to drip on the cluster. Our temps can still get cold enough that you do not want a damp or even moist cluster to have to fight for warmth to survive. Just keep an eye on it.
PS - still do the sugar on several sheets of newspaper, on the inner cover (it makes it easier to cleanup).
If ventilation is an issue, you can add a super (shallow/medium) above the inner cover for a dead air space.
You could also notch the inner cover for an upper entrance (if so desired).
When combined together, the outter cover wll be raised enough not to imped the inner cover notch.
A little inner cover opening is easy to defend and should minimize robbing issues, while allowing ventilation and egress.