WTO rules say that Free Trade Areas must benefit many sectors, not just one or a few. The EU and UK could make a broad FTA to keep most benefits of the Customs Union and Single Market in key sectors. They could coordinate tariffs and relax Rules of Origin to mimic a customs union, and use Mutual Recognition Agreements for Single Market-like access. This deep integration falls short of current levels and may limit the UK's trade policy independence. However, it can still follow WTO rules by treating all Member States equally.