Wrapping unlifted datatypes without pointer indirection?!

Say you have an unlifted datatype U

type U :: UnliftedType
data U = U1 | U2 <params> | ...

For better ergonomics, typeclass instances, etc., you also want a lifted wrapper L

data L = L U

Unfortunately it seems that this wrapper would incur an additional pointer indirection, somewhat reducing the benefits of using an unlifted type in the first place.

Is there a way that GHC could provide such lifted wrappers but without incurring a pointer indirection?!

(Background: In unordered-containers we're considering using UnliftedDatatypes for HashMap: https://github.com/haskell-unordered-containers/unordered-containers/issues/463)

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