Of course, if you've ever dug into running sql queries,(with Heidi, etc), there is always other little things to help compensate for item storage.In the following example, it will set all items stackable to 100, (that were stackable to begin with) and also set the weight reduction to 100 on all 8 and 10 slot bags. But this can be played with for the individual preferences.
Code:
UPDATE items SET stackable = 1
UPDATE items SET stacksize = 100 WHERE stacksize > 0;
UPDATE items SET bagwr = 100 WHERE bagslots = 8 AND bagslots = 10;