Exactly. Treat the force-field like the borders of reality itself. That confines us to only the present moment -- the Earth is hurtling through space so fast that where it was a moment ago or will be a moment later is on the other side of spacetime relative to the field. We couldn't even stay dematerialized for the same reason. But! Point to point transport on the island, quick as a wink, or at any rate fast as the materialization cycle will allow for. Five or six winks, maybe.

D'you think it would work?