Plugin to Automatically create gallery from uploaded images

I’m creating a simple user generated content site, and I anticipate that many of my users will not be particularly tech-savvy, so I need to simplify my processes as much as possible.

I need a plugin which will allow users to upload images to a post, and those images will automatically be displayed as a gallery on the post in a pre defined (max) size and format. Uploading the image should be enough for the image to be displayed on the page, and there should be no need for the user to have to insert the image into the post, or manually create a gallery.

Even better would be if the image uploading was integrated into it’s own metabox on the add post page, rather than through the button above the editor, which some users may not find too obvious.

These feels like it may be a fairly common requirement, but I’ve drawn a complete blank. The nearest I’ve got so far is this excellent tutorial, though it doesn’t quite go far enough for my needs:
https://wp.tutsplus.com/tutorials/plugins/how-to-create-an-instant-image-gallery-plugin-for-wordpress/

Can anyone recommend something suitable, I’m pulling my hair out here ??