Sigh...Ollie, to put it crudely, as I was trying not to do, you have ego issues. I think your idea about the UVB works great, and for that I would say that it is your choice.
Other than that however, you are simply neglecting Methos75 posts. See, you state quite early that you have observed that your Savannah likes the sand better than moist soil. This is certainly falsified, I guess you could say it is equivalent to saying a snake likes you because it does not bite you. Fact is, the snake does not like you and never will.
Whilst Methos75 states that the savannah's need humidity, and that is indeed substantiated with studies and the lot, you ought to make a compromise by mixing a dryish soil as A.gigas has stated. You cannot simply assume that a well respected monitor picks up a sandy area as its own, and the others are subject to moister regions, that's just ridiculous.
Additionally, when methos describes the experiences he has with Savannah's, it does not make sense for you to say that anything that goes against your idea is offensive, that's just nonsense, further more, again it is well substantiated.
Whilst reptile keeping is not an exact science, the basis has always been achieving either a basic environment that the animal can survive in, though not naturally, or by reaching similar scenarios as the natural habitat. That has always been, and will be, the way of choice for a long time.
You're a great reptile keeper, but you have to learn to understand the fundamentals and keep your own emotions in check with logic.