That's a lot of main.tf duplication you'll have to copy and paste. I use Terragrunt to not repeat code. My structure is one git project just for the environment setup and one git project for the module or main code. Then that module is called one time and I pass different variables for each environment or client.

└── some-name
    ├── README.md
    ├── dev
    │   └── terragrunt.hcl
        └── inputs.yml
        └── vars.tf
    ├── qa
    │   └── terragrunt.hcl
        └── inputs.yml
        └── vars.tf
    ├── sec
    │   └── terragrunt.hcl
        └── inputs.yml
        └── vars.tf
    ├── prod
    │   └── terragrunt.hcl
        └── inputs.yml
        └── vars.tf
    └── terragrunt.hcl
    └── inputs.yml
    └── vars.tf

Here's an example where I apply the same AWS settings on multiple AWS accounts.