As a former web hosting company owner (~20 years), I have a few areas which I can advise on;
- Don't run multiple companies. Your marketing budgets will not just double but would triple or more
- Know when your health is a priority (physical or mental) - at that point, employees are good to have
- Let your customers know exactly who you are, what you have experience with, and how you can help
- Know when you need to hire outside help
- Support does not have to 24x7, however, server management and monitoring MUST be 24x7
- You should have a priority queue system to allow critical tickets to send alerts
- Use an automated setup system like WHMCS or other
- Know when to hire
Yes, I listed "know when to hire" on there twice. It's a critical part of maintaining a healthy business. At some point, you just CAN'T do everything yourself and provide the very best service.
When I started, I offered web hosting only to clients that we had done designs for and then opened the door to friends of clients. It wasn't until 2000 we opened the doors 100% to random people. By 2002, we had over 500 clients and due to support, I reached out and had someone come on full time (they were actually a client at the time, and then turned 100% to employment with me).
By the time I was done, we had thousands of clients, 10 employees, hundreds of servers. I would not have been able to manage this on my own. I sold the hosting company in 2014 to expand my wife's SEO and Design Company.
If you're going to provide the very best, you need to know when you need help in providing that level. You simply can't give 100% to hundreds of people.
I don't agree that a knowledgebase classifies as 24x7 support. I think it can help reduce the support requests, however, 24x7 should be an actual person providing support. We had 2 people working overnights and 5 people working during weekdays, reducing down to 2 people working on weekend days.
Running a secondary company ads extra strain. I'd much rather see you merge the clients into a single company, then put 100% marketing effort into a single entity.
That's my two cents anyway, but each person is different.