How long is a long time? Could you just buy two PAYG sims at a time and keep one in your suitcase? Just buy a pin online a day or so before your flight to USA and pick up a new sim before you leave for your next trip.

Tracfone has "supersize" option to keep PAYG credit valid for a year. This calculator helps estimate cost https://www.reddit.com/r/NoContract/...ne_calculator/

There are other mvno's who have annual plans like RedPocket's 1 year plans on eBay.

Truphone and Piranha Mobile are easy to keep active with a call/txt unlike most US offerings where topup credit expires. International billable action to keep it active is fine since they're both roaming sim products. The rates are more expensive than tracfone but you're basically using it as backup to wifi or to tide you over until you get a new tracfone sim?