Regarding file size
I thought, ST runs on Windows, MacOS and Linux? But on iOS? With many programs, that can write JPEG, it is possible to set the compression level to a lower value, which results in smaller file size at given resolution. For example, I sometimes use IrfanView (Windows Freeware) to do this:
Another possibility would be to upload the file to a file hoster like DropBox etc., if you have an account somewhere.
But don't waste to much time on it ...