You have strayed in to the Camping section, you'll probably get a better response if you post again in the Caravan section. I don't have any knowledge of the Marauder but the fuse box is usually located near the mains inlet and battery, probably under a bed but may be in a wardrobe.
Amazing family weekend with old steam engines, classic car displays, market stalls, and full catering and bar. And camping on site - Save £25 by booking in advance.