The tools don't exist to make a good Epic in MOO, as you indicated
I may have been in error. I did some websearching. As you might expect, 95% of references on "master orion" turned up links to MOO3 and MOO2 material, but I did find one highly useful and well taken care of site.
I found a number of tools there: saved game editors that can do a variety of things, including choosing which races are assigned to the map, editing planets, and more. These are all old DOS tools, almost as old as the game itself, but I've tested them today and they seem to work.
Now the inherent limitation of any editor work is that the scenario designer will have spoiler information, but that's par for the course. I'm not sure that I can edit some of the subtler things, like which diplomatic and strategic bents are chosen for each race, and that sort of thing, but this is at least a great deal better than no tools at all.
I'm afraid that removes one of the larger obstacles to assembling MOO events. This could get ugly.