Adding/removing nodes in a block structured schema

I am experimenting with a simple, rigid schema, like so:

  text: {},
  fields: {
    content: 'fieldname fieldval'
  fieldname: {
    content: "text*",
    marks: ''
  fieldval: {
    content: 'text*'
  doc: {
    content: "fields+"

It seems that the default editing commands don’t allow me to either delete fields with backspace, or create new ones with enter. What would be the recommended way to get something like that working?

Demo here (based on the notes/notegroup example): Glitch :・゚✧

Thanks for any help

This seems like it will require completely custom backspace/enter handlers, yes, since the normal joining and splitting behavior is never valid in such a schema.