I've extended visa exemption many times and never been asked for this tm30, only time I've heard of it is on these groups to be honest. I might just be lucky or maybe my accommodation has sorted it out for me without me knowing but I've never taken one with me just told them where I'm staying and given address
I've used this all over the world and works everytime, book it on the way to the airport its a real booking that cancels itself after 48 hours and costs $16.