This was always the solution. The DUP is just going to have to accept that they cannot prevent ID checks - that would effectively mean holding the entire UK hostage. Unacceptable.
For the DUP, if they agree to a border in the Irish sea it ends their entire raison d’etre. That will destroy them permanently, so they will oppose it.
BoJo I feel will get tacit consent from Sturgeon in return for a indyref 2 agreement.