It seems like there should be an easy way, but no system that evens out babies and dreads is going to make it possible for others to compete. Unfortunately the matchmaking system does not account well for immortal-only offenses. Until that is fixed, you'll never be able to reasonably balance the major groups of players.
Even if you just try to even out high trophy vs. low trophy per hour and forget the immortal issues, any time you make it all about opponent DCR people will inevitably sandbag:
A has all training of minions and spell levels done.
B does not.
A at natural (unsandbagged) trophy level has harder opponents than B under matchmaking.
Even out A and B by giving A just enough bonus stars to level them across an hour of play (the proposal above).
A and B now do equally well in the tournament, all else held equal.
A sandbags trophies somewhat below B.
A and B now have even target DCRs, and even bonus stars per raid.
But A has stronger minions and spells than B and can therefore score total stars faster than B.
A therefore gets more stars per hour than B if A sandbags (and more than A gets without sandbagging).
Following this through, anyone who wants to win in tournaments should sandbag.
It's slightly more complicated than this, but not much, and I don't think the complications are enough to leave a useful gap in the logic.
The only way to avoid this is to make the bonus stars at higher ranks substantially better than at lower ranks. Sandbagged A then does worse than natural A, and A chooses not to sandbag. But B now does substantially worse than natural A, and the whole purpose of basing stars on target DCR and stars per hour is foiled.
I've discussed elsewhere why current matchmaking ensures that any simple additive formula won't work. When I get a chance I'll try to briefly summarize a proposed solution to again in the suggestions forum. It does make use of the idea of evening out stars per hour - but involves more than target DCR.
Bruce Campbells Army of Darkness - an open lv 40 guild for casual players of all levels who want to develop their dungeons and get Dreadstone in tournaments
Game Center: agoodspellr