Stylus-Activated Pie Menus? Tablet Mode Sculpting? How to access pie menus when in Tablet mode?

In Tablet mode, the keyboard will not be accessible, thus requiring access to the Pie Menus via the stylus pen. I need these menus for Viewpoint shortcuts, switching design modes, etc. 

Please Help. TIA
You can map one of the pen or tablet buttons in Wacom Tablet Properties to Ctrl+Tab as per this list of Blender shortcuts. Note that you can create a specific setting just for Blender.

Go to Wacom Tablet Properties
Optionally, set a specific application
Select the dropdown menu for the button you plan on changing
Select &quot;Keystroke...&quot;
Press Ctrl+Tab, optionally name the shortcut key, and then click on OK

(click images to enlarge)