I hesitate to suggest it as it is controversial to some but for Spearfishing I dive alone.
Initially by default, I didn't know any other spearos (it was less popular back then I think), but later through choice. But that may be something about me, I like (many but not all) other people but in moderation

. I enjoy being alone too, to think or not.
Yes, a well-trained and/or "with it" buddy might save your life. But they also might spear you, spook your fish or stop you diving, for example by their absence. I usually dive with various combinations of family on-shore. Only one has ever speared with me. Another sometimes swims or kayaks nearby for short periods.
A year or two ago a tourist spearo (German I think) tried.to hook-up with me I think, mid-dive, after I had approached rocks near shore ( but far from beach). I was lining up on a large grey mullet and he spooked me and the fish at the critical moment

. Fortunately it turned out to be a long, fishy day
So, I have mixed feelings about it

"Your mileage may vary" as American friends sometimes say
Bill's boat sounds like a nicer option though