What about the "it used to be a thinkpad" franken-laptop, painted in watermelon green stripes, with bits of the case sawn off and extra peripherals stuck on wit

What about the "it used to be a thinkpad" franken-laptop, painted in watermelon green stripes, with bits of the case sawn off and extra peripherals stuck on with duct tape. Or the slightly easier "cyberdeck in a suitcase" system which might (for example) be a full up diagnostic workstation once opened and unpacked. Lay something like that down and people pay attention. Sometimes they call the police, depending on the place. People get so tense in food courts. as to clothes, at that point your audience should be feeling lucky you're wearing some, not picky about the details.