Keep up the good work, guys! I can see that both of you enjoy the game big time as well as its challenges
Zhuangzi, I would propose that you leave the skull as it is and use something else, if you have it (Dragon Necklace will do). You have 30 battles + a few suppressions or item upgrades at most, which will push up the battle count to 300-305 at most. That's only 35 battles. The skull reduces its counter by 1-3% each fight, and you need to be really lucky in order to get to to 0% by the end of the game.
Have fun on your camping trip. I'll be doing something like that on Saturday - a hiking trip. 24 kilometers