I'm still having a bit of a mental struggle with this aspect. Firstly I enjoy the initial contrast in the animatic of the large father and the smaller son. The fact that he's a greedy git means that it might help the story to make him a bit fatter though.
In terms of his character, I don't want any of you feeling too sorry for him. He's meant to represent one of those spoilt kids you see in the supermarket running rings around their parents making up noise. A bit of the annoying little brother about them too, a bit like Myles in Moesha.