Looking at the one you linked looks like "large bed is just a normal single bed size, not a skinny caravan bed. However sleeps in it would have to crawl from the foot end to get in bed.
The ad says it sleeps 2 so the other would be the dining table folding down to make a bed.
I haven't seen it in the flesh but I think that pic is likely a bit misleading, I think that bed would be at least double bed width at the top which would be ok for them, having to climb over each other like with their Jayco isn't preferable so this is a good option as achieves that without needing the foot print of an island bed. The dining table is just that, not a bed.
edit, here is a pic of a same model but from a different angle