Spaceships campervans come with heaps included. Sleeping & cooking gear is included.
However, towels are part of the optional accessory range. You can add the All-In-One Accessory Pack ($195), which is the most complete accessory package there is and includes towels.
1x Camping table
2x Foldable camping chairs
1x Mosquito/bug nets
1x Solar shower
1x Chiller bag
1x Extra set of sheets (bed linen)
1x Set of 2 towels (1350 x 700 cm)
1x Set of 4 gas canisters
1x Sunshade
The total value of that list of accessories is $268... And it's all included in the All-In-One Accessory Pack which is just $195. Add this or other accessories when booking online or add it later via the Online Check-in Portal.
Or you can add a Linen Pack ($90) which includes an extra set of linen - duvet cover, sheets & pillow covers - and a set of 2 towels (1350 x 700 cm).