The boilerplate you mentioned has the node server, MongoDB server, and client (react) static files... What do you mean by: "a separate instance of the boilerplate running on each of the 5 websites."? A different instance of mongo/node/client for each website? Let's chat first, I might be able to help you with that.
More about me:
I have been working as a full-stack web developer for the past 3 years. React/Redux, NodeJs, and MongoDB is my main development stack. DevOps knowledge such as deploying a website in AWS or Google Cloud Platform, Docker, etc..
Experience in all major programming languages associated with web development, such as Java, Python, PHP, Perl, Ruby...
Also, I am aware of a variety of libraries and technics that might improve the project needs, such as TypeScript, Redux-Saga, RxJs, styled-components, Selector, Material-UI, Apollo GraphQL, Swagger, and so on.
Feel free to see my profile or ask me any question.