Can I ask you "How much time, effort & money" has running a free panel cost you?"
Unless you know the answers to the questions you are asking here, you should be questioning whether running a hosting company on a free panel is a good idea.
If you know the basics and don't know how to do all of the administration, this is where a paid for panel comes in.
- They do all of the work.
- Release incremental updates often.
- Offer support when it all goes wrong.
I don't know the full story here, maybe you only host your own sites, but usually if a customer is down for a significant portion of 24 hours and they don't have too many sites to think about moving they are a lost customer, especially if they are on a monthly contract.
Hosts will tell you that customers are hard fought for and easily lost.
We started out doing everything free in 1999 thought Open Source was great. Why pay for anything?
As you scale you realise it's all about the quality and reproducibility, as you won't have the time to constantly fiddle.
I shudder at the thought of hosting without a panel if you are multitenant.
This wouldn't have happened with CPanel or DirectAdmin which would cost from $5 to $15 a month for a VPS.
Have a think about the time and money this has cost.
I know these words don't help you now, but think about the next time this will happen, and without a panel, it's likely something will happen again at some point.