15" wheels on a '99-'06?

[68C1087GTA]

I know it sounds backwards & all & I'd rather not hafta sit here & explain why I'm asking. All I wanna know is IF a 15" wheel would fit & what would the maximum backspacing that will work. I know the rotors &^ calipers will be a clearance issue which is why I'm asking about the backspacing. As far as width goes? That is irrelevant at this point (custom bodywork).

I thought for sure I'd find an answer by searching & looking for drag race trucks, but I couldn't find any '99-'06 trucks with 15" wheels.