Free standing tent a.k.a Big Top Tent (opcional equipment)
A side tent was available as an optional accessory, like the pop top and the roof rack.

This tent is commonly knows as the 'Big Top Tent' or 'Circus Tent'. It's free-standing so you can mount it without the needing of your bus. There is a boot that connect the tent with the bus and make a small tunnel between the tent and the bus. You can leave your camping stuff inside the tent and drive your bus to visit places without any worry about carrying all the stuff.

During the SO-42 production this tent suffered minor modifications like the colored entrance.

Nowadays the Big top tent is a very hard to find part and prices are reaching constantly.

Dave from the UK made exact copies from Big Top Tents.
3 different styles of Big Top Tents were available...
common style
rare
rarest of rares
M-code: B42 and D42 means a SO-42 westy with side tent.