You should add sand for the liner to be right too, sorry about that. And as far as lowering the high end, I suppose it would work, exactly the same, only backwards. It would be alot more work though IMHO. It is always easier to fill than cut, but however you look at it, I suppose that it would also require you to look at what would be easier for you, if the dirt is higher on the outside of the pool on the low side then go for the high side. Like if it were dug into a hill like. Do what is easiest that is for sure, but do it right, you will not be sorry.