On either your engineers or ANZAC Diggers you have an option that you can select to place your barbed wire barricades horizontally instead of vertically. (This button is pointed by the upward facing arrow located on top of the scroll down arrow looks like palisades Green color background is for vertical and Red background is for Horizontal)

As for when it's best to have these barricades build early in the levels. Of course be wary of the blast Radius of the Fougasse Mines.

Interesting. How does one go about doing that?

This is what I mean

https://steamproxy.com/sharedfiles/filedetails/?id=1458252761

And this is the End Results

https://steamproxy.com/sharedfiles/filedetails/?id=1458324370

You should have lined the areas where the Takasago Volunteers with barbed wire and Fougasse Mines. The barbed wire will help slow down the Takasago to not only allow your troops more time to engage them but also makes the Fougasse Mines to be more efficient in Barbequing the pesky jungle fighters.