I don't see a point (or yours for that matter
) If one combatant has a superior space advantage, they get the benefit of orbital bombardment. Orbital bombardment itself is not the problem, its imprentrable-ish fortresses, which orbital bombardment counters. So in this case, Exar Kun couldn't hunker down on Yavin 4 if driven back. Because Mandalore would blow his temple to pieces.
And yes nukes are banned, but orbital bombardment via laser cannons (see Taris) does not count as a superweapon.
The way I see it, minus Exar Kun = Mandalore victory. But Exar Kun is in the Kaggath (Ulic-Qel Droma isn't however, so him destroying Basilik war droids is an invalid point - not to mention the fact that he is considerably better than your standard dark jedi) so the tide turns.
Exar Kun could face and easily defeat Mandalore in person, but he has to get to him first. I don't know if Mandalore has a specific base so I guess it would be on his flagship. So he has to confront Mandalore's flagship, and board it - which requires some sort of space advantage...
The space advantage also hinges on ground advantage as that determines resources, territory etc.
So we have to consider, how to the combatants armies weigh up?
Krath <> Mandalorians?
Dark Jedi <> Mandalorians?
Massassi Warriors <> Mandalorians?
Sith War Beasts <> Basilik War Droids?