Examining the AT&T travel policy, our account has an upper limit of $150 a billing period for the international roaming fee. It does state the second phone on the same account is only $5 a day. So pay for 10 days of two phones in the same billing period and anything past that is free. We haven't tested this, but once you hit $150 in fees, all gravy after that. I think last time (March 2020) we only turned the phones on a couple of days as we were in USVIs as well.

We did just buy hotspot specific for the Digicel 4G frequency (Hauwai purchased used on eBay) and signed up for Google Fi which has unlimited data anywhere in the world. I'll report back at the end of the month if this was worth the $120 total we spent for the 15 days we will be down. The hope is that Google has negotiated decent 4G speeds with the local carrier. If not, maybe next time just get a Digicel data plan (not unlimited, have to go to store in Road Town, can't set up and test before trip, etc..).

The thought is the dedicated hotspot will always be on and allows 15 devices to always have connection (two families online for weather/boatyball/workemail/kindle/reservations/wificalling) without messing with the iPhone tethering. Backup plan is a spare iPhone as hotspot and Google Fi, but in our experience it's a bit clunky.

We'll report back after this month! (thanks for all the previous posts on this forum for guiding me on data plans andn finding the correct 4G frequency hotspot).