I'm in the same boat. I'm travelling from the UK in just under 30 days....But I leave before this ride officially opens. I signed up for a D23 membership last week in expectation and hope they'd be previews available. So far so good.
I probably wont receive the card before travelling, but based on that ratatouille preview for D23 members, I read that email confirmations were enough. Plus it's not hard to log into to the D23 website and have some ID to prove you are who you say you are. And seeing they've changed the number of tickets we can purchase (4 to 2), it seems pretty likely that we'll get tickets providing we're ready to buy when they go on sale.
I can't be going all the way to Disney World, and miss out on this ride! Ha. Good luck!