Thanks guys. My wife tends to just roll her eyes when I engineer something (even when its to her benefit as it often is) so its nice to be appreciated!
I thought I would update this after some actual use. Mounting it on the inside of the side window sounded like an ideal hedge against it falling in the drink but it turned out to be in the way of whomever was riding shotgun.
Placing it behind the helm is ideal but only works when the girls are aboard as the folding chairs are usually stowed there when its just a fishing trip.
Putting it back on the outside of the side window when the chairs are stowed behind the helm really isn't so bad. Its out of the way and my rods are light. After using it this way all day it was still so well stuck that I think I would have broken either the plastic rod holder or the glass before the suction gave way. Being able to actually see the integrity of the suction through the window is also a big plus. Considering the modest weight and quality/cost of my rods, I'm not too worried about this location having now used it a few times.