Re: "the country has an advantageous business and digital tax environment"
"At some point you have to start thinking about just what we produce in the EU or the UK or wherever you're thinking about."
Plenty. We have full employment, growth, bounced out of the recent great recession and handled it considerably better than the Euro area. With a 2 year negotiating period and extensions we have had years of uncertainty yet still are chugging along without the doom and destruction some remainers hope for.
"Pretty well everything we make or grow can be done by someone else somewhere in the world cheaper, especially if a little dumping allows them to destroy the UK capacity to produce it."
Ok, so why isnt it? The bollox answer of the EU doesnt fly since they have plenty places of similar criteria that you mention. Also if things can be much cheaper (not mentioning quality, capacity or productivity) then why dont we want that? Do you want to pay premium prices for something we can get cheaper? It would be a pay rise to have lower expenses and as demonstrated with China dumping steel and the US tariffs, the tariffs were far more damaging to the economy.