I ask you to forgive me in advance if my knowledge is incorrect because of which I may mislead you.
at the entrance to the base there is a yellow mailbox, which, as I know, is a storage facility available immediately for all saves of one game mode. you can try to put the necessary things into it, for example, a map, a shovel and the rest necessary to achieve the goal, and after receiving it, put everything back, taking it away in the main save.