This and this do put things in perspective a bit more, and makes Ms Saunders sound a lot more reasonable. And let's be serious - we are nowhere near the point where we can say that most rapes are successfully prosecuted and that innocents being unjustly accused of rape is a bigger issue than real rapists getting away with it. Or, to quote from the Telegraph article:

Around 85,000 women per year are victims of rape in the UK, of whom 90 per cent know the perpetrator.
The most recent figures showed that just 15,670 women reported rapes to the police, often because they thought it would be impossible to prove the offence, or because they did not have any confidence in the police’s ability to help them, with only 1,070 convictions resulting from the 2,910 cases that got to court.

I think the main problem with your article is that he talks constantly about situations where both parties involved are drunk. The police guidelines in question, especially if you look at them in context, are more concerned with cases like what you describe, men who aren't drunk, or much less drunk anyway, who purposefully look for drunk girls who are more likely to consent, or in any case not refuse. Which honestly is a much less grey area. It's not so much about drunk sex as it is about soberly taking advantage of drunk girls.

No doubt there are cases of accused rape where both parties were drunk out of their skulls, and in such cases I do think that the alleged rapist's own drunkenness should to some extent shield him from the accusation of not having obtained proper consent. But those are just a drop in the bucket next to all the cases of real rape - most of them not related to alcohol I'm sure - which continue to go unreported, or which are reported but still end with the rapist walking free. Nobody except tabloid journalists is talking about absurd scenarios where men need a woman's signature on a contract before engaging in sex - this is about more successfully increasing the conviction rate of all those rape cases that fail or aren't even started at all now.