The Mondeo estate can take a (6foot3inch?) double bed in the back, with the tailgate closed and the front seats only slightly moved forward
With the lightening on mine it puts the payload up to about that of an Escort van (740kgs- many cars are a fraction of that) - so its a huge space/ weight
but the biggest single thing thats probably been in the back is me!
ive had a full size commercial bouncy castle or two (2 at the same time) pro (thousands of watts/ massive speakers ) PA systems with lights in the car - no problem - its the way you pack it - you have to watch your springs, though
Thats why ive kept my car so long (+ the performance/ economy, and it runs on veg oil) + the investement/ work done