REI and similar stores are full of hiking shirts which would fit the bill. I'm sure they can work in between a base layer and a thin jacket.

You can always wear one of those lime-green high-vis vests, or stick a slow-moving-vehicle triangle on your bike, or use a bright red light.

But in general, I don't think that high-vis clothing helps much. At night, lights will do the job. During the day, if a driver doesn't see you it's not because your clothing wasn't bright enough, it's because they were fussing with the radio, or a child, or their GPS, or on their cell phone, or just not expecting you. (Read up on inattention blindness for more info.)

Granted it can't hurt. But I don't see a compelling reason to wear blindingly orange bike jerseys, and thus my cycling clothes tend to blend in a little better.