60 Gal Breeder Gap???

Hey so I bought a 6 gal breeder and I’ve been wrestling with it all day.

I think I’ve relied too heavily on googled AI answers because I was in a rush and now im completely confused.

I have a gap that is about 1mm across various sections of the length of the tank, even when I’ve levelled it.

I’ve added additional 3/4inch thick exterior plywood in case what came with the tank stand was warped

How much does this matter?

Can I support it with a foam of sorts ?

Any and all advice is appreciated as this is my first tank of this scale and I don’t want it exploding on me further down the line