Nor do I, unless revised limitations are worked out, and adhered to.
However, let's be honest, the vast majority of PPLs (or for that matter, a very large proportion of commercial pilots and aeronautical engineers) have never been trained how to do this. Calculating flying limitations wasn't even on the syllabus when I was at ETPS.
And even then, you have to be a good enough pilot to stay within those new limits - and that doesn't apply to most PPLs either. When an aeroplane was certified, part of what we did was ensure that the flying characteristics were such that inadvertently exceeding the envelope was very hard - but that was only assessed within the cleared envelope, and may not be possible in an unofficially enlarged weight and CG envelope.
In short, it's not big and not clever. If you need to carry more load, get a bigger aeroplane!
In my book, safe trumps legal every time. However, in this instance, it's both unsafe AND illegal - and thus a no-brainer. The fact that you are probably uninsured as well just re-enforces the point really.
G