You know, here's a depressing idea for an edit:
Lando blows up the reactor and everything happens as it does: Luke gets out and Lando gets out and yells YAHOO! and all that (though I would still thin the fleet outside).

But instead of showing the Death Star blow up as it does, do an ID4 showing the explosions from the weaker reactor underneath the skin of the DS, which remains intact. The DS then does a STAR TREK 3 and enters Endor's atmosphere, where you then take shots from DEEP IMPACT and show the bulk of the DS hitting Endor and wiping out the Ewoks, Leia, Han, Chewie, R2, 3PO and everyone else -not destroying the planet, but just causing a lot of damage around the impact zone.

You would end the movie with Luke taking Vader to the area where his friends used to be to put his body on the pyre. Since it is at night, you could alter the treescape and skyline to reflect a forest that has been pulverized with a shockwave (like after a forest fire).

This way, Lando and Luke survive, but damn near the rest of the cast dies as a result of the rebel attack (talk about consequences!) due to unforeseen circumstances. This is not so much for JEDI:R as it is an idea for any editor to use.