I had an idea like this a while back. It could be called a Retainer Delivery Service, to make it a bit more lore friendly (if that matters). Or maybe Mobile Moogle Mail?

There could even be a fee required to make it into a gil sink. I can't speak for anyone else, but I'd be fine paying let's say 1k per day or week to use it in towns. And maybe 2k to use it out in the field. The fee could be said to cover their travel costs and time to bring your materials to you. I mean, it would save me cash on warping back to the towns.

This would be a great help for Culinarians, and maybe it could be worked in for fishers as well.