Hi Alouette,
Something like this would work:
https://www.unitedhobbies.com/UNITED...hless_Inrunner
As the hull is closed, I'd prefer an inrunner, as it's easier to watercool it.
You could use an outrunner, but finding one that would spin slow enough might be a challenge, they have plenty of torque, but would have to be oversized to compensate for the lack of cooling.
Regards, Jan.