I've been wanting to do something like this for years and then I met a really cool man whom had far more skill then me and got to the task of making some trenches and bunkers for my 15 men.
Here is what he has come up with (given my ramblings and dimensions).
If anyone wants them ill be offering
1x 8" trench section
1x 4" trench section
1x4" HMG /Gun trench section and roof
2x trench end sections
1x trench to bunker connector
1x trench to bunker door-way connector
1x 90degree trench section
plus a small and larger turret ,which fits my modular weapons slots rather well.......
Everything colonial world needs to keep the hordes out :)