Using the new Story Maps, is it possible to have custom thumbnails for map slides within the Sidecar block?
So far I haven't been able to find a way to replace the stock 'map' image that is being used as the thumbnail (see below). I was hoping to use Sidecar as a workaround for the Map Tour block because Map Tours don't allow audio, but having a Story Map with 10+ slides of that basic map thumbnail is very unappealing.

A secondary (less important) question I have about the Sidecar block is if it's possible to remove all of the unnecessary white space between each slide? Tinkering around with the CSS in the inspector, it seems like it's just a simple padding setting.
Thanks!