These are very old set ups but if it helps this is a 70x40cm roborovski setup which shows how much you can get in with 2 wheels (zoozone 1 which is same size as duna multy). Looking back at this it’s bigger than I remembered! Ignore the level - this was taken when they were both elderly with a slim chance of falling out imo.
If you want two 8 inch wheels then I’d go bigger, this is an 80x50cm ferplast Mary set up (for two winter whites)
