Issues Customizing Save As tab in Backstage

[BillPars]

I need to address two related issues in the following Custom UI for (32-Bit) Access 2016 on (64-Bit) Windows 10:

<customUI xmlns="http://schemas.microsoft.com/office/2009/07/customui">
    <ribbon startFromScratch="true"/>
    <backstage>

        <!-- Hide Home tab. -->
        <tab idMso="PlaceTabHome" visible="false"/>

        <!-- Hide New tab. -->
        <tab idMso="TabOfficeStart" visible="false"/>

        <!-- Hide Open tab. -->
        <tab idMso="TabRecent" visible="false"/>

        <!-- Hide Info tab. -->
        <tab idMso="TabInfo" visible="false"/>

        <!-- Hide Save Database As task on Save As tab. -->
        <tab idMso="TabSave">
            <firstColumn>
                <taskFormGroup idMso="SaveGroup">
                    <category idMso="FileTypes">
                        <task idMso="SaveDatabaseAs" visible="false"/>
                    </category>
                </taskFormGroup>
            </firstColumn>
        </tab>

        <!-- Hide all but Print Preview task on Print tab. -->
        <tab idMso="TabPrint">
            <firstColumn>
                <taskGroup idMso="GroupPrint">
                    <category idMso="PrintCategory">

                        <!-- Hide Quick Print task on Print tab. -->
                        <task idMso="FilePrintQuick" visible="false"/>

                        <!-- Hide Print Dialog task on Print tab. -->
                        <task idMso="PrintDialogAccess" visible="false"/>
                    </category>
                </taskGroup>
            </firstColumn>
        </tab>

        <!-- Hide Close button. -->
        <button idMso="FileCloseDatabase" visible="false"/>

        <!-- Hide Account tab. -->
        <tab idMso="TabHelp" visible="false"/>

        <!-- Hide Feedback tab. -->
        <tab idMso="TabOfficeFeedback" visible="false"/>

        <!-- Hide Privacy Options button. -->
        <button idMso="ApplicationOptionsDialog" visible="false"/>
    </backstage>
</customUI>

When a database opens using the above, its Backstage displays the following, which seems correct:

Screen Shot A

If the user opens an object (say, a Query Definition), then it displays the following, which also seems correct:

Screen Shot B

If the user closes the database object, however, the Backstage does not revert to Screen Shot A, as I would expect.

Additionally, if the user then clicks the "Save As" button -- with no database object open -- the following error message displays:

Error Message

Issue #1: How do I get the Backstage to revert from Screen Shot B to Screen Shot A without closing/reopening the database -- or otherwise avoid the error -- when no database object is open?

(I assume my Custom UI is incomplete and/or conceptually flawed.)

Issue #2: How do I hide the "Advanced" option ("Save As Client Object"), which is grayed-out and unavailable -- but still visible -- in Screen Shot B?

I find a "SaveAsClientObject" entry in the "AccessControls.xlsx" file (from the Office 2016 Fluent User Interface Control Identifier download), which I assume corresponds to this button.  I cannot figure out where to put it, however, by simply reviewing the API Reference for the CustomUI Namespace.

My naive interpretation of Custom UI elements in Screen Shot B is:

Screen Shot B (Annotated)

AFAIK, a Custom UI to hide the "Advanced" option "Save As Client Object" would look like this:

<!-- Modify "Save As" tab. -->
<customUI xmlns="http://schemas.microsoft.com/office/2009/07/customui">
    <backstage>
        <tab idMso="TabSave">
            <firstColumn>
                <taskFormGroup idMso="SaveGroup">
                    <category idMso="FileTypes">

                        <!-- Hide "Save Database As" task. -->
                        <task idMso="SaveDatabaseAs" visible="false"/>

                        <!-- Hide "Save As Client Object" button in "Save Object As" task. -->
                        <task idMso="SaveObjectAs">
                            <group idMso="GroupSaveObject">

                                <!-- AT LEAST ONE UNKNOWN WRAPPER NODE BEGINS HERE. -->

                                    <!-- <button idMso="SaveAsClientObject" visible="false"/> GOES HERE -->

                                <!-- AT LEAST ONE UNKNOWN WRAPPER NODE ENDS HERE. -->

                            </group>
                        </task>
                    </category>
                </taskFormGroup>
            </firstColumn>
        </tab>
    </backstage>
</customUI>

I cannot figure out, however, what nodes wrap the Save As Client Object button within the Save Object group.  A "topItems" node?  A "layoutContainer" node?  Something else? Beats me.