<appSettings>
    <add key="webpages:Version" value="2.0.0.0" />
    <add key="webpages:Enabled" value="false" />
    <add key="PreserveLoginUrl" value="true" />
    <add key="ClientValidationEnabled" value="true" />
    <add key="UnobtrusiveJavaScriptEnabled" value="true" />
      <add key="RichTextEditorTempPath" value="\\path\to\public_html\rtetemp" />
      <add key="RTE.AjaxUploader.TempDirectory" value="~/rtetemp" />
      <add key="RTE.ImageEditor.TempFolder" value="~/rtetemp" />
  </appSettings>

Have tried without them as well, the folder exists.