Offer a package that automatically adapts to varying requirements without having to commit to a Goodybag.
The idea is fully described in a two-page pdf document. Ask if you would like it emailed directly. See:
Being on holiday and finding that the only connection was 4G. Though this worked well, I made bad choices of which size of Goodybag to buy. I would like a scheme that was more flexible and didn't need clairvoyance.