My understanding is that currently Steam Workshop currently does not permit the uploading of plugins larger than 100MB.

Have you perhaps already hit this size limit with one of your projects? If so, please describe your mod below.

Assuming it is not possible to have unlimited file size for uploads, what size do you think would be big enough for most of the larger mod projects? For example, if it was increased slightly, to 200 or 300MB, would that be helpful? How big is ideal (considering there will likely be some limitations).

You could also allow ESM files, which would allow people to spit up larger projects. I can't help but be kind of disappointed at the fact that Moonpath to Elseweyre limited its size for Steam Workshop. Had they been able to use an ESM file for the main plug-in, and then esp files for voices, the creator could have added a lot more content.

As for truly huge plug-ins, I would just offer a teaser version on Steam, and redirect to another site for the full version.