First, I do not recomend hovabators, toooooo small. Also, I see no reason to add water bottles, that is odd to me. Adding water bottles is merely another secondary method of having mass, and thats whats needed, mass. The medium should be as large as possible. Then theres no need for water bottles. The Perlite mixture(50/50)is both your temperature mass and humidity mass. I also never add water during incubation. If your adding water, that means your losing water excessively. Why would you lose water????? If your losing to much water, then fix that problem, not patch it.
Ben is right about the air holes, I have them in lots of lids and not on others. If i had one clutch, then no holes is fine. If I have five or six clutches in one box, then i use air holes.
Its all about conditions and no one answer. Its also all about your conditions and thats what makes advice on hatching eggs difficult. Heres the real deal, good monitors eggs are very easy to hatch. Bad eggs are not so easy to hatch. Bad eggs come in many ways, from infertile, to dead fertile, to weakened living eggs. The last group has a low hatchrate. The last two groups are based on suitable nesting. But all said and done, a good strong clutch will hatch without incident in all sorts of temps and conditions.
The reason hovacookers are not so good is, they lack mass. So they can and do change conditions, which is not a problem, they just change them to quickly for varanid eggs, they like to change slowly.
ALso, all you can do is set them up, which you have better done already, then maintain them. Which is to not allow to much change. Then all you can do is hatch them or not. You cannot muck with them and have a benefit. Mucking with them usually results in failure. No worries mate, if these fail and you support your ackies, they will throw more at you to muck with. Cheers