Many thanks again to the forum member here who've given us guidance - it's been very useful! Maybe just a little more? Unless we hear reason to do otherwise we'll start booking hotels on this route soon.
A few particulars: When we bike tour I "tow" my 7 year old daughter with a Swiss-made followmetandem (see it by quick Google search if you care to) for 85-90% of each days ride. As such we limit mileage to under 60k a day and have some shorter days. Routes are designed to be as flat as possible.
There are several train rides on our journey. We are used to/comfortable taking bikes on trains in Europe.
Arrive Charles de Gaulle PARIS 11:15am. TGV to LILLE or TOURCOING. Train or Uber to KORTRIJK.
Arrive KORTRIJK mid to late afternoon. Pick up rental bikes. Set up. Bags in lockers at station.
Ride less than 30km down the Shelde river to OUDENAARDE hotel.
30 minute train ride OUDENAARDE to GERAARDSBERGEN (avoiding the hills of the Flemish Ardennes).
Ride 54km down the Dender river (and then the Schelde again) to SINT-AMANDS area hotel.
Ride 50km from SINT-AMANDS down the Schelde then up the Rupel river to LIER.
Train from LIER to SOME PLACE about 30-50km from GHENT, maybe this place is DENDERMONDE and we'll ride a up a section of the Schelde we haven't already seen to GHENT hotel.
Train with bike to BRUGES. Ride 45km back to GHENT hotel for second night. Or just stay in GHENT this day if we are tired, or train to Bruges without bikes if we just don't want to ride. We have visited Bruges two times already ...
Depart GHENT by bicycle, ride 35km south toward OUDENAARDE along another part of Schelde we haven't already ridden. OUDENAARDE train to KORTRIJK (or ride entire way). Depart KORTRIJK by train at 16:15 for LILLE then TGV to Loire Valley for 3 night in Amboise where we'll start a different bike tour.
This last day we are the least sure of. Maybe it is better to first train GHENT to OUDENAARDE or nearby, and cycle up the Shelde back KORTRIJK? Maybe train GHENT to DEINZE first and then ride up the Leie river back to KORTRIJK?
What do you think? It seems like a busy schedule, but the cycling only takes between 2 and 4 hours each day of pedaling and we feel pretty happy to just relax around our destination town after that ...
Thanks very much!