If you wish a recent comparison of the relationship options parliament/government is currently musing over with regards to commercial trade in goods, you could try this:
http://researchbriefings.files.parliament.uk/documents/CBP-8309/CBP-8309.pdf
It's not particularly bad, although it manages to both over- and under-estimate the problems facing the Max Fac option at the same time. Over-estimate because most controls (be they UK or EU) can take place away from the border and, indeed, frequently do so already - the Motis and Stop 24 operations being 2 cases in point. In fact with railfreight, there are no border controls that I am aware of. Under-estimate because it seems to fall into the on-going trap of equating A customs union with free circulation of goods - wrong, and once again Motis/Stop 24 are examples of controls involving customs declarations, collection of taxes and statistics, and checks on goods.
