12C sounds mighty cold, I don't think I could do a 60 minute dive wet in 12C, but cold tolerance is a very personal thing. You may be part polar bear.
I say camera first, you miss %100 of the shots you don't take.
but caveat I enjoy photography
I did around 500 dives before buying a drysuit and the course was an absolute waste of money/time to me. Bought a camera after 50 dives. When you dial it in a drysuit is a very stable platform for photography.
If you already say you feel you are comfortable on %95 of your dives, that translates to me that you would enjoy taking photos on %95 of your dives.
12 C is absolutely drysuit territory for me but also if I didn't take a camera I probably would not dive. Monterey appears to have some WA opportunities so that may work in your favour.
Head on over to Wetpixel for camera related info, there is some excellent knowledge there regarding all things underwater photography related.
A few shots below from Qld Australia
I say camera first, you miss %100 of the shots you don't take.

I did around 500 dives before buying a drysuit and the course was an absolute waste of money/time to me. Bought a camera after 50 dives. When you dial it in a drysuit is a very stable platform for photography.
If you already say you feel you are comfortable on %95 of your dives, that translates to me that you would enjoy taking photos on %95 of your dives.
12 C is absolutely drysuit territory for me but also if I didn't take a camera I probably would not dive. Monterey appears to have some WA opportunities so that may work in your favour.
Head on over to Wetpixel for camera related info, there is some excellent knowledge there regarding all things underwater photography related.
A few shots below from Qld Australia