I don’t think this is a good solution to the Brexit process. Being in a permanent customs union will prevent us from doing our own trade deals, contrary to what you suggest, and will make the country poorer – thus making it more difficult to reverse austerity and protect the poor. It will also leave us subject to EU rules without having a say over them (except as some kind of external lobbyist). “Staying close to the Single Market’ is a euphemism which disguises the fact that in order to have full access to the SM we would need to accept freedom of movement and state aid rules.
Above all, this touted deal will mean that we leave the political framework of the EU which is the most successful multilateral project yet devised to promote peace and stability, resulting in the most peaceful period in Europe’s history. That is a very big price to pay.
If there can be no other way other than to have some kind of Brexit, I would accept a compromise Norway-style arrangement which would leave us in the Single Market – and thus not losing full access for the 80% of our economy that is in services – and with a customs union. This, of course, is still a considerably worse deal than staying in the EU – and I would prefer that we have a public vote with an option to remain – with the Norway arrangement as the other option. I believe a majority in the Commons could be built around just such a joint offer of a public vote combined with Norway: a parliamentary motion to enshrine a Norway-style option as our agreed aim in the Political Declaration along with a commitment to ratify this decision with a public vote.