I just found an example of exactly this!
A "Portable" steam engine is a precursor to the Steam Traction engine. Because they weren't self propelled, horses usually towed them to work locations.
They took a 10 hp Ruston and Hornsby Portable Steam Engine and threw it onto a barge!


Published by youtube user "Peter Little" on Aug 4, 2019
Murray River Paddle Steamers
https://www.youtube.com/watch?v=4gyT8okcBq0A recent trip on the PS Alexander Arbuthnot from Port Echuca along the Murray River. The PS Alexander Arbuthnot was built as a barge in 1916 and converted to a paddle steamer in 1923. She is powered by a 10 hp Ruston and Hornsby Steam Engine.
Not that's 10 HP! Look at the boat move....
-CB