Here's exactly how to get the trophy for essentially "doing everything". I've tested many theories out and I'll tell you what exactly works. Note, I got my trophy on October 7th, 2019.
First, complete the campaign on any difficulty.
Second, plan to do the rest in one sitting. The campaign is the only thing with saved/tracked progress, so everything else has to be done in the same session without quitting back to the PS3 menu.
Here's what I did:
3 co-op maps, can be done online or with 2 controllers. Please note, if you do it online, the Host is the one who gets the credit for the completion of the map.
3 single player survival maps - just finish wave 1 and let the game tell you that Wave 2 is beginning. Don't quit out, let them kill you when you're done. Afterwards, press circle to go back to the main menu, and ignore the warning about not saving progress.
1 single player Prologue - do it on Rookie.
On the final scoreboard screen for whatever is your last of the 7 maps, you'll get the trophy notification.
Thanks!