Dave - You're in the same boat as us - well perhaps not literally! Our plan is Strasbourg to NL in August and we have similarly found that the options are just 3 - via the Rhine all the way to say Weesp (690 km, 6 locks, 51 engine hours), or the Sarre / Moselle / Rhine from Kolblenz (850-86-102 hrs), or the Moselle / Rhine (900-84-107 hrs). We plan to go the Moselle route as delay in the hopes of the Meuse (850-163-143 hrs) opening up in time to reach NL seems too risky.
I believe you are just over the 20 m legal limit for pleasure boats on the Rhine without a pilot, so you may have a tricky decision to make! I travelled the Rhine from Strasbourg to beyond Tiel in 2019 and the river police seemed totally disinterested although we were 2 inches within the legal limit of 15 m then allowed.
Good luck. Peter