It all depends on the campervan model, some Spaceships campervans can seat & sleep 2 people while others can seat & sleep up to 4 people. Here's the overview for you.
Alpha, our budget model, can seat & sleep up to 2 people
Beta, standard campervan, can seat up to 4 people and sleep up to 2 people inside the campervan
Beta 2S, the premium model, can seat & sleep up to 2 people
Beta 4-berth, the only campervan with a rooftop tent, can seat & sleep up to 4 people. It is perfect for travelling friends or a family with (small) kids.