Well that's probably beyond me, I haven't tried delving into the code and I have no idea how much extra memory is used per item.
I shall remove the two extra items I added last night so I can play the game then, I got everything in I wanted to (for now) except for a few extra base defence weapons so it'll tide me over until a solution is forthcoming, even if it's "We don't want you putting that much extra stuff in the game, get stuffed modder!"