What’s the approximate size of the viewing area? I’m guessing it’s rather intimate as its in a static caravan. Also, do you have any idea of the approximate depth you have available? If deep enough, you may be able to fit a 2.1 system in there with a bit of creative ingenuity. Last 2 things, budget for parts and places where you’ll be looking to buy. That way we can make sure we’re all on the same page.
For a bar with that height, I’d start by looking at something along the lines of the PC-83. It has a really nice full range graph (as full range as a driver that small can go), so you might be able to get away with not needing a tweeter pair.