I have already described viable routes through to the NeverNever Castle to Winter Knights Apartment at Arctis Tor, Arctis Tor Dungeon to Demonreach.
The Problem would be that every time he used it he risks being accosted by Winter Courtiers remember Mab’s Ball? It would go from the tedious to the suicidal.
The Winter Court would have its own version of a Peabody, a joyless bureaucrat, Mab’s Chamberlain who wants Harry’s paperwork in triplicate (one for each Queen, though I suspect Mother Winter as an Intellectus appreciates the toilet paper).
It will also have those who would challenge Harry’s position in the Court trying to obstruct him (he must take at least one of them along to Demonreach with him and leave him there in stasis for a bit)
Also perfect for Mab to ambush Harry for updates on the wedding etc.
It may be shorter, but it will seem much much longer.