How to make collision for an object with a intensive displacement? Shader displacement.
There is a way in BP to calculate blocking volume size and position on a sliding scale and increment it.
Its just math.
I don’t know for sure but you would probably use variables in the material editor to control the size and position of blocking volumes you would have to spawn in and manually
place around your materials that are displacing.
That is just my thought 
Might be a nice feature to add if collisions can be displaced along with meshes / materials in the material editor
The other thing that might work is changing the shape of another mesh that you give 100% transparency so that the player cant see it.
Then you give it nice and tight collisions and change its shape using morph targets.
Then you line that shape up to change its shape 'in sync" with your material displacement.
So you essentially morph an invisible capsule
Here is a good article on morph targets and collisions:
(If you make that little bridge 100% transparent you will never know its there. Then you line it up with your material / shader displacement )