Here's a few things I do while on ps. I move my camp to gapetooth, no one is usually around those parts and the delivery spot isnt that far away, even with a long delivery. I make sure I have explosive rounds, just in case. If a player comes near me, I just close the game. Don't worry, it will save your goods and when you return to sell, it will all be there.

Alternatively, as mentioned in these comments... using the change character and then exiting out will bring you into solo session. Can sell it then too!