I ended up giving the wordpress api a go, and so far things are good. I found it easier to build an example post in the UI, retrieve the post using the API, and then use the retrieved fields to build a new post.
Need help for deleting a WordPress Cookie with setcookie() Not Working
Include custom post type that matches taxonomy field in another custom post type
How to hide or change mobile header logo with Additional CSS or custom PHP
Blog page shows the whole blog post instead of the excerpt or summary with the feature image only
Use https://developer.mozilla.org/en-US/docs/Learn/Common_questions/Tools_and_setup/What_are_browser_developer_tools to determine: Are the URLs absolute or relative as seen in browser source? Is the path correct for the images that throw the 404’s? If you changed domains, take a look at https://wordpress.stackexchange.com/search?q=CLI+change+domains
WooCommerce Checkout – Validate User Role
Creating dynamic URLs for Product Pages
The stupidest and fastest way, if you have a source code backup, delete all the previous files and re-upload the backup file.
How to change the url of the author to a specific page?