To flog a dead horse just a bit more, turtling doesn't really work. You need to have some way to force monsters to pay attention to you. Something like
http://community.wizards.com/go/thread/view/75882/19856162/A_little_Lock_build_for_you...this, or perhaps a crusader.
If you're absolutely set on dual wielding shields, I'm afraid that you can't shield bash with Tower Shields.
Shield, Tower
This massive wooden shield is nearly as tall as you are. In most situations, it provides the indicated shield bonus to your AC. However, you can instead use it as total cover, though you must give up your attacks to do so. The shield does not, however, provide cover against targeted spells; a spellcaster can cast a spell on you by targeting the shield you are holding. You cannot bash with a tower shield, nor can you use your shield hand for anything else.
Emphasis mine.
Also, I believe that unless somehow you qualify, you can't gain a shield bonus twice to armor class. There are ways to circumvent this, such as the Ironbound prestige class, from Helm and Hammer.
http://www.dandwiki.com/wiki/Ironbound_(3.5e_Prestige_Class) Either way, animate the shields. It costs a +2 bonus, but it frees up your hands for a two-handed reach weapon.
If you want to tank, go Crusader. If that's not available, try the Knight class from PHBII.