5 Days between tours

go to France or Germany or Switzerland

Since you will be on two active tours, packing and unpacking, changing hotels, moving from place to place, how about using your 5 days to take a vacation from your vacation? Pick a city with atmosphere, lots to do, or a place you can wander and do nothing, and stay in one apartment or hotel the entire time. I’m thinking Paris or London but there are many options.

I think staying in one place is a great idea. It could be a major city, or it could be a base from which you make some short day-trips. You'd want a place with good plane or train connections to Sicily and Brussels(?), so I think a spot in western Germany where you see a bunch of gorgeous towns would be a good possibility. Fly into Frankfurt.

I'd add at least one night before the tour to Ghent. I've not done this tour and I see the itinerary is changed a little to spend the whole day in Ghent but I'm sure there is enough there for at least a 2nd partial day. You might want to add another day if you want to see any of Brussels.

Other than that, I'd go for Paris as well but I'll choose Paris every time, lol!! It's such an easy train ride to Brussels and on to Ghent.