Hi flat, I thought this too when I refurbished the chassis as the cage-to-chassis points are structurally very heavily welded. But it's only eight points of contact/it's just metal...and now refurbished, I don't intend to do this for many years to come...
eta will make me look after the chassis even more!
eta#2 - just rethinking this through [you got me thinking...], if body needed to be lifted/removed, I simply unbolt and remove external roll cage and then unbolt and lift body. It's part of its clever mated through the body design - so not too much extra work