Extra wheel trailer and you dont have to do Anything to the Bike .. just put your stuff in the 2 panniers on the trailer
Its not much More than another fork with a 2nd front wheel on it.
We see people Touring the Pacific Coast All the time towing BoB trailers behind their Road Bikes and BoB trailers weigh More. & have a smaller Wheel .
Only thing you change is the QR Skewer ..
https://www.biketrailershop.com/extr...er-p-1377.html
maybe put a nicer wheel in it ( even a Dynohub wheel and charge your E Toy Batteries . USB)
I wouldn't hang a Beam rack off a Domane even if you add a metal seat post.
there is that Isospeed elastomer De coupling the seat tube from the rest of the Frame above the BB ..
loading more weight on that via a Big saddle Bag may have undesirable consequences