Graham - sailing is very 'stately' (a.k.a. slow) with the cassette motor.
Managing to cram all the RC gubbins into the Mantua hull is an achievement, however tidy/untidy it is!
Like you, I had to decide how much of the solid bulkheads and keel I could safely hack out without
weakening the structure too much.
Good luck with the maiden voyage when you get to make it !
Richard