I believe (although could be wrong) the proposed changes in the thread Proposed Changes and Restrictions For Implicit Conversions (2. Bulk Extensions > 2. Allow the qualifier of an export clause to be an expression instead of a stable identifier) would cover your usecase, too.
So something like
export (impl: MyTrait1 & MyTrait2).*
should eventually be possible, as per my understanding and if everything goes right with said proposal.