Say you take a perfectly sweet steel track fixie and slap some BOB Nutz on the rear. Say, in a fit of mental aberration, you hitch up a trailer to it, 'cos it Just Fits (what, on a 120mm hub? apparently so!). And say, just hypothetically, you tool around hilly countryside picking up boxes of turnips. You'd learn these things:
Trailer + Fixie does work, but it's gloriously daft! That trailer is a damn ANCHOR when you hit a steep spot! Track bikes have whippy-ass chainstays of death!