Making Passive Perception more Fun

I've had a love/hate relationship with D&D 5e Passive Perception since I first read the rule.  On the one hand, it's nice to have a simple way to resolve whether or not the PCs notice something without tipping your hand as a DM and calling for a WIS(Perception) Check.  On the other hand, the static nature of the Passive Perception takes some randomness out of the game that I miss.

When I design a dungeon, I don't want to know that the PCs will notice a secret door with a DC of 15 because of the highest Passive Perception in the party.  I still want there to be a chance that they don't notice the door.  On the other hand, I also want there to be a chance that they do notice a door that they normally wouldn't based on Passive Perception.

My solution is to pre-roll a number of WIS(Perception) Checks.  Each PC gets a row on an index card, and I first write their name and their WIS(Perception) modifier.  Then I partition the card into a number of columns, make some dice rolls, and write down the results.  When I need one or more Passive Perception values during play, I look at the next result on the card.  Once I use a value, I scratch it out.

In this way, I can keep the suspense of Passive Perception, and still have the uncertainty that a die roll brings to the situation.