I would not go for fatter strings. Yes they do have a little more material moving about in the magnetic field of the pickup(s). But: A a stiffer string has less amplitude, due to more tension. So that makes more material, but less movement. I have had many brands, kinds and sizes of strings on my cheap Ibanez GSR200EX, but the output accross the board has always been fairly even.
Just a cover of a real bassist
Beaten and beaten up by time