Loading data with split records via SQL*Loader

I have some csv data files with long text fields and some of those fields are enclosed by quotation marks but split over multiple physical records. I have located a document here suggesting a solution using CONTINUEIF LAST or CONTINUEIF NEXT. This is good in many cases, but not universal, it depends on the structure of the input file, the beginnings or ends of the continuation lines must be uniquely identifiable. For example, if we use CONTINUEIF LAST PRESERVE != '"', it is guaranted to work only if all "normal" (i.e. having no continuation) lines end with a quotation mark, which is not the