I'd try to do both. The Caravan job, may lead to PIC or a better job. Still it's only got one engine, so it's still pretty worthless. Do the CFI thing, get all your ratings and teach multi. Mutli time is gold. Work on that.
I took a part-time SIC job in a Part 135 twin turbo-prop that lead to a PIC twin turbo-prop job. SIC in a single pilot plane can be good as it does introduce you to new types of flying and leads to better job/flight time. Just remember to use it and move on.