Field canvas not showing

[chrisrowe]

We're wondering if it's possible to utilize a Craft thumbnail instead of the original asset for the canvas image preview. I'm attaching a screenshot from a situation where the client has an S3 bucket with signature authentication headers required for assets. Craft is able to generate thumbnails from these assets in the panel UI, but not for the canvas field that is trying to load the original asset url. Basically, could there be a toggle field added in the plugin that is something like 'Use Craft Thumbnail for Canvas'?