Thanks all for your replies, links, and reassurances that trains are a viable option.
As we are city dwellers who don’t own a car, I chose races that were easy to get to without one: Antwerp on the 23rd and Gavere on the 26th.
Bonus would be Zilvermeer on the 22nd, which is not far from Antwerp as the crow flies. It all depends on train connections.
Sharing our plans here in case anyone else wants to plan something similar. If you don’t already live in BE or a bottomless bank account, it can tricky logistically with Xmas closures and demand pricing.
Antwerp was an easy choice because
a) can easily walk to race. Hubs can drink all the beer he wants.
b) CX aside, it’s a cool city and like all Flemish cities will look cheerfully festive for the holidays
c) it’s big enough to have at least a few restaurants open on the 24th and 25th.
Evening of 25th, train to Oudenaarde, which is only 12 km south of Gavere.
I booked a hotel with a restaurant for Oudenaarde, instead of a vacation rental as I assume grocery stores will all be closed.
After we come back from Gavere, pick up bags at hotel in Ourdenaarde and then train back to Paris. Alas I need to be back on the 27th.
No riding for this trip: Antwerp area isn’t terribly inspiring for a roadie, and we won’t be in Oudenaarde long enough. However thanks to links above and what I’ve found while searching there’s lots of cool places to stay. I’ve found inspo for a spring visit.
Most vacation rentals in Ourdenaarde area assume you’re there to ride, with secure bike rooms, good laundry facilities and sometimes even power hoses!
Reddit had also been a source of good practical tips: