Laravel multi-tenant SaaS - vendors with customers

Question

After 48 hours of research on Multi-tenant SaaS approach with Laravel, I got some idea about it.

1. Single code-base, shared DB
2. Single code-base, multiple DB
3. Multiple code-base, multiple DB

I chose to go with option 1, since the project budget is small & this is my first SaaS project.

My problem over here is with Vendors (with own domain) having their own set of customers.

I'm using zizaco/entrust for role management here.

So the main thing is, I'm not getting an idea of how to do it with Laravel's default AUTH middleware. Since, a customer should be able to register with different vendors. How do we manage it in users table of default laravel installation?