I'm nearing 60% completion on placing shoring on one half of the trench sides. The other sides may not get done. Gluing wood sticks to styrofoam is not nearly as fun as it sounds.
I also don't know how to stain the wood to make it look more realistic or even if I should.
The shoring method I picked was poles or logs as opposed to superior planks I've seen on other boards or old photographs of really happy clean British plank shoring trenches (must be propaganda or training areas).
The second pic is a sample of my overly pitted ground between trenches. I will add vegetation and dirty water to the crater bottoms when I finish the miserable burdensome all work and no play task of shoring.
The out of period soldier models are painted craptacularily by me and appear at least digitally to be extremely glossy.