Invert Y-Axis Water Spray in Super Mario Sunshine

So what I want to to be able to do is flip the Y-axis in the water spray mode in Super Mario Sunshine. I am running the game with Dolphin and am using a gamepad. I do have it set up and have inverted the camera X-axis already.

Running around is fine, but the spaying water, just.... Up is up. Down is down. I'm not flying an airplane, why are these controls "backwards"?

I could invert the Y-axis controls on the Control Stick but then to run forward I'd have to be pulling the sick backwards. Ridiculous; this would make platforming a memory hell.

I'm hoping there is a way to open the game files and change one little value for the water controls... Or a mod I can install or something, But I'm not finding anything.

It may be possible to do with an action replay. However, if you are using an emulator (presumable Dolphin) you can achieve this using the following steps:

If you are using a Gamecube controller, make sure your adapter is set to PC instead of Wii U.

Right click on Controller Stick Up, and add the following:
([your input for backward] & !([your input for R])) | ([Your input for forward] & [your input for R])

Then, right click on Controller Stick Down, and add the following:
([your input for forward] & !([your input for R])) | ([Your input for backward] & [your input for R])

You can invert Up and Down only when R is fully pressed. This will allow you to spray while running by half pressing the R trigger, just like the original Gamecube controller.

An example (full press threshold = 90%):

Up:

(`Left Y+` & (`Trigger R` < 0.9)) | (`Left Y-` & (`Trigger R` > 0.9))

Down:

(`Left Y-` & (`Trigger R` < 0.9)) | (`Left Y+` & (`Trigger R` > 0.9))