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You can either get wider wheel hexes (the kit ones are probably 5 mm). You can get 6, 7, 8, or 9mm hexes to widen the stance. Even bigger ones are available, but they might be too wide then for the axle (you won't be able to bolt the wheel on).
Otherwise, you can get offset rims, again, these come in a variety of sizes, but will widen the stance, without moving where the rim bolts onto the axle.
(ELI5) Can you "space out" rear wheels?
I have a TT02, and an aftermarket shell. The rear wheels sit quite inboard of the shell at the rear and looks a little... shonky?
Front to a lesser extent, but might also need moving outwards a little.