Good idea!

I too believe you should have rudders w/o holes in them.

I am also a little concerned about the open servos in the floats. If they get wet, they may fail on you.
Have you got them water-proofed?

How do you plan on keeping the line from getting into the prop?

I'm looking forward to seeing your first fishing trip with this. Do you have video capabilities so we can see it in action?