Perhaps instead of going with a triple wall to cut off the opponent's side of the board you can force push/teleport them into a corner then cast just two walls.
This benefits would be:
-They can't move around so when you cast a creature you know that the creature will be able to attack next round.
-It's more mana efficient.
-Gives you a bit more versatility in your hand.
-Gives you less walls to worry about reconstructing.
Also a few things you should consider. First is a mass dispel, especially against a wizard.
The next is a mage wand with dispel on it. The opponent could use their economy advantage (because of your mana drop on the walls) to counter your every play then get ahead of you.
