REST support for CustomPress post types

Hello,

on one site, we are running WordPress simply as a backend and communicate via the REST interface. When trying out CustomPress - which I like for it's ease of administration - we found out, that without fiddling with the plugin's code, we couldn't set show_in_rest to TRUE in register_post_type.

Found neither a option to do so nor a filter to change the arguments. Did I miss it?