You can hide doodads models. If they still have collision I believe that the collision will stay the same.
Note that destructables are different!
Here is an example. you can reverse this function by playing the doodads unhide animation if I remember right.
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Actions
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Animation - Play the hide animation for all doodads of type Fire within (Playable map area)
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Animation - Play the hide animation for all doodads of type Cattail within 128.00 of (Center of (Playable map area))
I don't believe that there are any other ways to interact with doodads in specific with the trigger editor. Even with using Jass.