Unless I dive with my daughter, girlfriend or brother, most of my dives are Solo Dives.
When on a Spearo dive (75% of dives), I'm Solo, 2 or 3 divers in the same ocean, but solo by all accounts.
I started Solo after 100+ dives and was very familiar with my gear and procedures.
Just get the necesary experience (you'll know when you got it) and if you decide to do it, be aware that you have to be more disciplined and conservative with your plan and under no circumstances violate the plan, if you're not ready to be disciplined, don't do it.
Consider using a surface float in case it's not mandatory in your area, so the cptn of the boat knows where you're and let him know your maximun time underwater so he can pull the line if the time pass and recover what's left of the diver (LOLOL sorry, local club joke). I allways surface 5min or more before the deadline time.
As for alone in your own boat diving, that's just plain stupid in my opinion.