The main reason I solo-dive is because my first experiences outside of a class was my dive-buddy disappearing before I even got below the surface. Since then, I've basically been solo-diving, and do take care to stay within the limits of what I think I could handle in a catostrophic emergency solo. Most recently upgraded to having redundant air, and wish I had just done that long ago.
If you do the math on how much health-insurance costs, and look at redundant as insurance, is extremely inexpensive insurance. My advice (if you haven't done it already) is to get some cheap regulators and a 19cu (or larger) pony-bottle to act as a redundant air-source.
I often dive from a boat, solo-dive, without "surface-support" other than someone watching the boat. It's my dive-buddy's boat, and we both solo-dive, with his wife or a friend watching the boat.
With nobody watching the boat, I'd be worried about the anchor coming free and the boat crashing into the shore. Theft might be another risk, depending on location. If it's a small or cheap enough boat, like an ultra-basic fishing boat, then maybe it's not a huge deal. I might suggest using two anchors.
Alternatively, you might consider going to a local popular dive-site, making a dive-buddy friend who also solo-dives, and then if they're cool enough offer to let them alternate dives from your boat. As someone who doesn't own a boat, I'd gladly take that deal, and split the gas, because the better sites in my area usually don't have easy shore-access.