The ASL Scenario Archive is the place to upload these, and vasl-templates has a feature that does it all for you (check the help). It uploads the VASSAL .vsav file, the vasl-templates configuation, and also automatically generates a screenshot of the VASL setup.
For example:
Grabbing Gavutu (look in the User Files tab near the bottom).
vasl-templates will remove the VC and SSR before uploading.
The ASL Scenario Archive lets you upload arbitrary image files associated with a scenario, so you could put them there.
There are also automatically removed.
Once uploaded, these files will be presented to users when they search for the scenario in vasl-templates e.g. try searching for Grabbing Gavutu.
Just make sure that vasl-templates is configured to get images from the internet (otherwise if people download the .vsav file, the labels will try to connect to a locally-running copy of vasl-templates). I kept forgetting to do this, which is why I added the
"Confirm settings before updating scenarios" setting, which forces you to check the settings before updating a VASSAL scenario file.