Unfortunately the Tango tickets are very restrictive - even if you have status, you generally pay a fee for changes.

As moorw003 mentioned, your ticket will be refunded for credit if you don't show, but I would assume that immediately rebooking on two same-day flights would be pricier than paying the change fee - and very tight, since you'd only have a 1h20m window between flights.

Your other option is to play a little with fire - try calling in the early afternoon and identify that you have an issue preventing you from making the first flight, and you were hoping to change to the next flight if there is space. Make it clear (nicely) that you're trying not to cause issues with AC by having a no-show, and perhaps they may help you out. I'd still plan on having to pay a change fee for a Tango ticket, but perhaps less.

Absolutely no guarantee, and I've only done it once where I arrived after the 45 minute check-in window - but I do have status.