I tend to stash a couple of monitors at the front corners of the stage. I don't have the luxury of flying them, though that's another possibility if you have flyable components and competent riggers available (as well as the appropriate anchor points, of course). For some shows, I've also added support on stage hidden in set pieces when needed for specific numbers.
There are some good options for small format speakers at reasonable budget levels. I have a couple of EV ZXA1's that get a lot of use at this duty. They are powered and can be found used for reasonable prices. They are small enough that you could fit one center stage or a spaced set of two and they won't have a large visual impact. The EV PXM-12MP is a bit larger but also sounds better and is a more flexible package. It's a wedge-format powered unit with coaxially mounted 12" and HF drivers. These would probably be harder to find used as they're still relatively new, but the price point is pretty good. They're still small enough to be pretty low-impact visually, and pack a surprising amount of power.
I promise I'm not just an EV fanboy. I do own both of these and have had experience doing exactly what you're trying to do with them, and can say that they both are quite capable. There are many similar options. I don't think I would consider a TV sound bar for this application. I suspect it will run out of clarity pretty quickly when pushed to the levels needed.
jonathan