Netlify CMS image widget + Zola

I’m attempting to setup a static site with Zola that has Netlify as a CMS. Netlify’s image widget adds variables to the frontmatter at the root level, resulting in a frontmatter that looks like this:

+++
title = "My Blog Post"
description = "A description of my blog post."
author = "Sam"
blogimage = "/images/uploads/my-picture.png"
+++

I’d like to access the image location from a template in Zola. However the following doesn’t work due to the fact that only predefined frontmatter attributes seem to work at the root level in Zola:

{{ page.blogimage }}
Variable `page.blogimage` not found in context while rendering 'blog-page.html'

The following would work, but I see no way to get Netlify to include the [extra] tag inserted into the frontmatter:

Frontmatter:

+++
title = "My Blog Post"
description = "A description of my blog post."
author = "Sam"
[extra]
blogimage = "/images/uploads/my-picture.png"
+++

Variable usage in template:

{{ page.extra.blogimage }}

Is anyone familiar with any options or an approach I could try in either Zola or Netlify to solve this apparent incompatibility? Thanks!