I can't. The IDE won't let me edit the generated code. Which I think is stupid.
I did find a work around: the generated code for the main is this:
I replaced it with the following to actually set a reference variable for the form:
But I don't understand why running that statement in the constructor would not have maximized the frame. I would think it would work no differently than the previous statement setDefaultCloseOperation and should execute.
Altering the main as I did works, but if someone can confirm for me if that will have other consequences for the application I would appreciate it. Or if there is another way to do it.