What do you want to be doing long term?
I second the idea of vaccine clinics (as a vet) - you can make great money this way, set your own schedule, and the work is not physically demanding. In my experience you tend to be working with inexperienced assistants though, which can complicate things. Shelter med is a good idea but in my (limited) experience tends to be very high volume/fast paced, so maybe not the best re-intro step. Could also look at GP relief without dentals/surgery.
In general, vets do not make good techs. Vets and techs aren't trained for the same things. If you were dead-set on a tech position, I wouldn't recommend a shelter setting as you might need to hit the ground running there. Vaccine clinics/Vetcos/Banfields might be a good option still - they are full service, but rarely get more complicated than monitoring during routine surgeries/IVCs/running bloodwork/xrays. ETA: I'd also consider tech relief, particularly if you are not anticipating needing to work as a tech for more than a year. You'll be hard to hire in this situation, tech turnover is already high enough without hiring someone who intends to leave.
I've had multiple vets (who had not passed boards) work as techs in a previous job and it usually didn't go well. They were new grads which was an extra layer of complication, not sure how much time you've spent actually in practice. You'd also have to be extra careful to respect the limitations of the position you hold, not the degree you hold...might be more difficult than you'd think.
Sorry final edit: CA requires techs to be licensed, not sure you'd qualify. Which leaves you with assistant positions