I did have a CMO/COO for my first company. Transitioned him to equity and cofounder status after a few months with him. It turned out to be an awesome deal. He got us acquired in the end because of his connections and hard work.
The thing is that for maximum stability, most businesses need a cofounder. Partly to bounce ideas off, to keep you focused and slap you when you get distracted, and to act as an emotional pillar when things inevitably go bad.
For a lot of solo founders, their real co-founder is actually a family member: brother, spouse, daughter/son. If your first hire is the only person you're bouncing ideas off, they deserve a co-founder title. An employee, even as a right hand man, will have much more difficulty shaking sense into you.
Another thing to consider is that putting someone as cofounder status makes this company their life focus. How much would that improve his performance?
It's normal for cofounders to not take put money in and take salary, they just get a much lower share. One digit equity normally. But the drawback is that one digit equity doesn't qualify for a cofounder status. Maybe you can start with 5% but offer to sell him an additional 10%.
