Re: "Common Sense" approach to rules (RACSD)
Rule 16 Tower Shields: How the #&%@ do they work?
At the start of their turn, a creature using a Tower Shield decides whether to use the Total Cover version of their shield, or whether to use it for a shield bonus. This is a free action. Tower Shields being used to provide Total Cover provide cover in all directions. You cannot make any Attacks*, as defined by the Glossery, while using a Tower Shield to gain cover. Actions which do not provide an attack roll are not attacks, and may be used while a tower shield is providing cover.
*Any of numerous actions intended to harm, disable, or neutralize an opponent. The outcome of an attack is determined by an attack roll.
Theory and practice are the same in theory, but differ in practice.