Better get very very good at configuration management, provisioning, patching, monitoring, and all the other things that go along with running large quantities of infra (even if virtual). I don't know anything about your app, but I do know many shops that deeply regret going down this path rather than building multi-tenant in the first place.

For what its worth, and some may disagree, but production SaaS apps don't belong on Linode/DigitalOcean... but that's a whole other topic.