You cannot replace just the rubber gasket.....it sits beneath the glass.
Also, changing the height of the closed lid may put extra stress on the Display Assembly which may make it more vulnerable to cracking (assuming the display lid could even close with a thicker gasket).
FYI, don't carry the laptop where you put pressure on the closed lid. This applies even when storing/carrying the laptop in a bag. Nothing else should be stored in the laptop bag other than the laptop itself or those items may put pressure on the display which may cause it to press against the keyboard.