you can get a steel hatch from an explorer, and weld that to the cab behind the seats. there will need to be a couple pieces to fill where the taillight reliefs are on the hatch but that's about it
some guys just cut the b2 hatch and use it like a tail gate, but it will come off entirely instead of be on hinges.
and you would just twist the latch like you would open the hatch, and it will come off in your hands
the best way of course would be to use bed-rails, and even the back part of a cab from a genI/genII ranger
or the even best way is to use a ranger cab on the broncoII frame, and bob the bed:
most guys run out of ambition before getting that far "welp, I cut all the structural strength out of it, it looks cool....i'll stop there"