If you’re planning to use your caravan off the grid you may want to consider an option with a Lithium battery.
The most common types are the 18650 type, which use a 18650 cell that can be 100 or 500Ah.
However, for portable music or video you can opt for a dedicated Solar Chargers offer a 12 or 24V lithium battery, like the LM823, for smaller caravan models, but they will obviously add a lot of weight.
If you’re really on a budget though, why not opt for a 12V smart battery charger for less