A couple of my lot have done removable rear ends but this is the only decent picture I have of either of them.
Both are done the same way with 2 rails on either side holding it all together. Rails are made from 2 square tube sections, one fitting snugly inside the other. The inner has a bolt at the end, the outer is capped allowing them to be bolted together to make a very solid rear.
They're not designed to be a quick access, the bumper and wings also need to be removed, but both cars run injection engines (one turbo'd) and can't be removed from the standard engine bay without major dismantling. This way is quicker and less disruptive.