Have you played Battlefield 1942 or any Medal of Honor games, that is how you should do it, but only if it would work.
You make a building as the wall. Have a bunker on the bottum
==_ _==_ _==_ _==_ _==_ _==_
{} {}
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== These are your large bunkers
_ These are MG post
|||| These barbedwire
{} Your bottum bunker
You make the man go through the bottum bunker, go up stairs or lader and then get out to the back of the pillbox to the trenches,
This is just my opinon