Thanks, unfortunately the solutions aren't simple, though I'm sure we'll do something eventually.
I'm wondering about a partial solution I could do on my side, an option to export the 7z without including the png files, to reduce the upload size.
For a lot of mods that wouldn't make any difference. The png versions of the texture aren't included in the mod that is downloaded in game. The pngs are really only included in the upload for people who want to make a mod derived from the original mod (if allowed) or maybe if the author's computer dies, they could get a copy of their mod with the original png files. Although we don't guarantee safe storage for mods, this has actually happened before. So there is good reason to have the pngs in there. But I wonder if there should be an option, when exporting from the editor, include png or not?