Adding additional team members to a maxed out team

We are a team of 20. We have 10 paid seats in our organization which are fully taken. Now that we’ve been working in Asana for a year, we want to roll it out to the rest of the staff but cannot purchase more seats at this time.

We want the new users to see the same teams & projects within our organization, and don’t want them working in a separate workspace.

Is the best onboarding process to invite them via their personal email addresses and treat them as guests?