RadRichTextBox and RadRichTextBoxRibbonUI are two different controls so there should be no problem separating them.
You can use the rich text box in flow mode so there are no pages, just the editing space. Here is a sample code:
As for the UI for saving a document and performing undo and redo, you can use RadToolBar. As long as you set the DataContext of the tool bar to the Commands property of RadRichTextBox, you can bind the buttons in it to the Undo and Redo commands and the SaveCommand, similarly to how this is done in RadRichTextBoxRibbonUI.
Don't hesitate to contact us if you have other questions.
All the best,
the Telerik team
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