I think it might be possible. I have done similar things in different games. What you might need to do is to download cheat engine. After that it sounds a little bit complicated but its really not that hard.
Tutorial of cheat engine will teach you what a memory address is (its really simple just finish the life tutorial (30 seconds tutorial) )
You must find the memory address of item.
Just save when you are about to finish the mission and get your item. Afterwards just drop your item and check if the state has changed pick up the item and see what states have changed (if this is impossible you can do other things just do something to change item state) . You should end up with few memory addresses that have changed after you do this for a few - to many times. (there are ways to be more proficient with this so if you are having a hard time ask me for hints)
after you have 3-6 memory addresses save them in cheat engine table (ctr+s if i recall correctly)
remember the values of the memory addresses. (write them down, there is another way but it might crash game during loads so this is safer)
after you do this load your game that you want to have the item in. your memory addresses should change to something different- change them back to the ones you've seen before and alt tab back into the game. if game crashes make a sad face, and next time avoid changing all of the addresses leaving one unchanged. If the game crashes again leave another address unchanged until it doesnt crash.
If game doesnt crash but you still dont have the item try two things.
First saving and loading the game.
second freezing the values so they cannot change once you alt tab back into your game.
if done correctly this should work
save your game and you should have the item next time you load even if you turn off cheat engine.
I hope it works. Tell me if you are confused about anything or worried about the program. :)