Any way to increase single channel guests or have a workaround for it?

Hi,

We are streamlining our agency communication with clients and are gradually moving as many clients as possible to Slack now. We are using 2 paid users (myself and an employee of mine) which apparently means we can only invite 10 single-channel guests. Obviously we need separate channels for each client, as it makes no sense to mix them up.

Unfortunately I only realized that there is such a limit after onboarding the first 10 clients and hitting that limit.

Is there a workaround for that or do I literally have to setup and pay for non-existent users only to get the additional 5 guests per user?

Thanks!