Hello there,
To add to the comments above, your base needs just a few tweaks and then should look better.
If you didn't fancy the idea of building a hedgerow or similar you still could do with beefing up the amount of vegetation. Normandy is very green, even in summer.
The sort of postion you have modelled might be better suited to the Eastern Front but if you want to stick with your Normandy theme, here are a few suggestions:
I'm no artist with a computer, but hopefully this makes sense. You want to add a ton of longer grass. If the field is pasture, rather than crop, then the grass would be mostly long. some wild flowers would add some interesting colour perhaps.
Add some spoil from the trench around the edges, also in front of the sandbags a little.
Put some corrugated iron or a barn door or something over the trench, then cover it with netting and or a Zeltbahn.

Some photos from near Caen of German positions.
Willy Klein:

Franz-Josef Kneipp:

A small extra, here's an extract of a British map showing some of the 12.SS positions in the area, how they were laid out etc. Blue is confirmed, red unconfirmed:

As you can see, they're mostly along hedges and boundaries, but some are out in the fields.
Hope this helps.
Cheers
Sean