Ok so 10mb is a little overzealous as I wanted to include several images. I am certain that some reasonable content could be delivered in the 1mb range as well.

On the Amateur Radio side, I would envision a direct RF link, where an HF receiver connected to a computer that is connected to your uplink data. The RF receiver would be receiving JS8Call over HF and it would place messages on the uplink for broadcast. Similar to the APRS data you are uplinking but eliminating the internet connection. This would allow Amateurs to send messages via RF to your uplink and the satellite would broadcast that message with blanket coverage. If you have any interest in this, I have extra radio gear and expertise in writing software to interface the JS8Call software to your uplink. Of course, all of this assumes you have direct access to the uplink without using the internet, which may not be the case at all.

Dan