Sorry, DT, but you don't seem to quite have the hang of the principles of the Schengen agreement. The European Commission's own website (no fear of "Daily Mail" bias) explains all here:
http://ec.europa.eu/dgs/home-affairs/what-we-do/policies/borders-and-visas/schengen/index_en.htm
In particular:
"Any person, irrespective of nationality, may cross the internal borders without being subjected to border checks. However, the competent national authorities can carry out police checks also at the internal borders and in border areas, provided that such checks are not equivalent to border checks. This is valid for cases when, in particular, the checks do not have border control as an objective and are based on general police information and experience. It's also valid when the checks are carried out in a manner clearly distinct from systematic border checks and on the basis of spot-checks. Under such circumstances, the police may for example ask you to identify yourself or pose questions regarding your stay, depending on the purpose of the check."
In view of this, do you really think the UK will be allowed to get away with routinely "conducting inspections of vehicles etc." (as they do now, particularly in places such as Calais) without having them considered "border checks"? Absolutely no chance. Schengen area nations conduct virtually no checks at their borders as the whole idea is to treat the entire area as a single borderless nation. Hence I stand by my contention that the UK is better off out of it and people here need to be aware of what a borderless situation with an independent Scotland as a member of the EU really means.