Unfortunately, I bought an expensive ticket abroad 2 weeks before my treatment is supposed to finish. That means I will wear my last tray while I will be overseas. It won't be until 4 more weeks that I can go back to home country and visit my ortho there to get the retainer.

What's the best solution in this case?

1. Ask a local ortho in holiday country to put the retainer (i don't trust them)
2. Wear my last set of aligners for the entire time
3. Ask my ortho to put a retainer for the duration of my oversea travel. When I come back, they remove the retainer and I continue with the remaining trays, and once done, I ask for another retainer (the final one).
4. Spend 1500 euros to book return flight ticket just to get the retainer from my original ortho in my home country.