Removing the rudder with the boat still in water is a bad bad bad idea. I had my cutlass bearing replaced on the dry and they removed the rudder (for other reasons)witch was a job and a 1/2. The rudder is mounted with thru bolts that was fiberglassed over.
There was some fiberglass work to do before the rudder was remounted.
Could it be possible to remove the
engine mounts and raise the motor enough to slide the prop shaft in instead of out?
Good luck, I think you are better off spending the money and taking the boat out of the water, but that just me.
Thomas