Honestly, just book after you return to the USA. On a recent 6-day WDW trip, I completely forgot about the window until a week late. I had set a phone calendar alert, but it must've gotten deleted because I didn't get it. At 53 days out, I was still able to get about half the places I wanted to eat, with a little time flexibility. Picked up all the others the day before dining, when people cancel to avoid no-show fees. Didn't need to stalk the website at all between the 53 days and 1 day before dining. And I decided to eat a couple places I'd never been before, just because their times were available. It was a great trip and not in any way inferior to when I've booked within seconds of the 60-day window opening.
I get it, food is absolutely part of the WDW experience. And booking those ADR's is always something I like doing. But it simply isn't true that late booking will fail, and it also can be quite healthy and enjoyable to try new things. So truly, don't waste money trying to book them on an expensive data package while onboard the ship.