What is the best user role? (for collaborative VM setup)

I am trying to invite users outside of my organization (i.e. B2B collaborative users) in order to share a VM. 

What are appropriate roles in the setting like this?

I DO EXPECT users to:

• Start/Stop/Restart a VM
• Connect to a VM(so that they can configure within the VM)

I DO NOT EXPECT users to:

• Look at resources not associated with the specific VM
• Change Azure network configurations (even associated with the specific VM)

The background scenario here is that I host & run multiple VMs, each dedicated for a single customer. In setting up a VM, I need help from IT guys of the customer company.