It would be great to have the ability to edit placed assets that can be edited with CSS like SVG files. This would provide further similarities between the prototype and production atmosphere.
Disregard, I just discovered this is already possible.
Yes, an SVG "island" of sorts is just a Group that you can double click to edit. Once the gradient editor, stroke position, and line cap editing is enabled you'll be able to edit quite a bit more to customize the imported geometry.