Thankyou for the photos and information. I had not thought of laying the servo on it's side.It works much better and operates smoother than upright. Thankyou again.Regards Keith

HI Keith
I restored my 34" Fireboat, and yes the space available does not allow an upright mounted servo. Not sure of the details re your servo but mine uses a standard size servo mounted sideways. You can then place a sunken deck over the fitting and retain the correct appearance. I am attaching photos of my model and the installation including the rudder detail. I used a brushless motor and LiPo to keep the weight down.
Hope this helps.
Good luck