Project Setup for Second Deployment

Company has completed first deployment of SAP (Finance) using an Implementation Project in Solution Manager. We are about to embark on our second deployment (Operations/Mfg). We'd like some advice on how to set up our second implementation project. A couple of facts that may affect the decision:

We know in the second deployment there will be many decisions that will have a significant effect on artifacts developed in deployment 1.

Deployment 1 implementation project will be transitioning to a Maintenance project within one month

We know there are options like:

Complete separate implementation project for Deployment 2.

Separate implementation project for Deployment 2 with Reference copy of Deployment 1.

Copy Deployment 1 into Deployment 2 and add ...

Which option of the 3 listed above would you consider and why?