I never had to check disk space, cron jobs or do any purging.
Where did you run you Mastodon Instance. I run mine at Digitial Ocean, been running for nearly a year and have not encountered any issues and I’m running on the cheapest server they have.
If you gave up running a single user instance of Mastodon then I really don’t think you should be running a Lemmy instance. It’s a fediverse compliant system that will have many of the same issues as Mastodon.
I run a small 10 person Instance of Mastodon and it runs very well on a small server of 4GB Memory and 100GB disk. Not sure why you had issues with a 1 man instance.
Out of interest why would you want to run a 1 man Lemmy Instance?
What’s the make/model?