Playing in World Cups, I think 3-5-2 is the best way to get the most out of our players and set up to frustrate the opposition. I can see our full strength lineup at Qatar being something like this:
Woud
Cacace Boxall Reid Tuiloma Payne
Thomas Bell
Singh
Waine Wood
Swap out Waine for Barbarouses, Woud for Sail, Marinovic, or Payne for Fenton, Roux, Elliot, Ingham if you'd like.
That's a pretty tough back 3 to get past, and allows Cacace more freedom to attack which will be crucial, also allowing Payne to get forward to swing in a cross. A spark of creativity with Singh sitting behind two strikers, which will take some attention of Wood and allow another target to aim at in the box.
I get people think 5 at the back is inherently negative football but we have to be realistic, even with how promising we look at the moment, we will be coming up against stronger footballing nations and will need to be able to set up defensively and counter well, I think 3-5-2 or 5-3-2 allows us to do that best