There are these things (thesignaljammer.com) but I could swear they used to be half those prices.
Those tend to piss people off and potentially attract unwanted attention. Use with caution.
They have a tiny AC plug one (thesignaljammer.com) but it looks like bullshit. But if the description is accurate on them I should be able to pick one that more or less only encompasses my vehicle I think.
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