I have no idea what connectivity options are available in current scanners, but it sounds like a viable solution could be to use an RF band that customers don't overwhelm, similar to wireless microphones perhaps, with a little hub situated nearby that consolidates the list of already-scanned tickets, possibly standalone or possibly on a wired network that includes other far-away entrances.
Was going to say it shouldn't be hard to run a wire around an entire stadium, but maybe some popup outdoor venues that might be complicated. Could use line of sight towers for fun.
