Very nice, however a point of order, technically the Walrus hull would be a 'motor-boat'.
And it is indeed something that has happened numerous times over the years, one example is the SARO A.19 Cloud,
OK-BAK(G-ACGO) that was used from just after the war up until the mid-60s as the motor launch
Delfin.
BTW, the sails and spars on the Rohrbach were there purely as auxiliary propulsion in case of engine failure,
and evidently it worked reasonably well.