You see, you kinda argued against yourself a little bit there.
Point: We agree that Revan would win the prolonged war. I'll work with that.
Let's look at the possiblities at Traya's options ('cause options win wars):
1. She can sit at Malachor V and attempt to erode Revan's army slowly with. But as I've already explained, Revan's logistics are too good to be eroded like so.
2. She can engage Revan in a battle. This way, she loses. Period.
note: Traya's assassins are only gonna help (significantly) in a prolonged war. In a prolonged war, Revan will adapt to the assassins techniques, meaning that the assassin's usefulness is limited.
Now for Revan's options:
1. Attack Traya at Malachor V. If he devouted many of his men to such a battle, then he loses the war. But he know's his master too well for this to happen. What would likely happen here is that he'd send a small portion of his force to Malachor, they'd be destroyed, and Revan would learn his lesson. He wouldn't make the same mistake twice.
2. Revan attempts to get Traya into an open battle. IF it worked, he'd win the war.
3. Revan sits out the war, starving Traya out. This results in a victory for Revan.
In the end: Traya just doesn't have as many options. The only way she wins is by Revan making a BIG mistake, which isn't likely.
I have now made up my mind: it's Revan's battle to lose.
Granted Revan has a lot of options in this battle, but Traya's options are deceptive options. You are underestimating the effectiveness of psychological warfare. Once Revan devises tactics to limit the assassins, what remains is a psychological impact on the troops. You don't know where the assassins are, they could be right behind you, they could be watching you while you sleep. This causes a number of psychological issues for the troops. Paranoia, sleep depravation. These cause a serious impact on the mental fortitude of soldiers, causing lapses in judgment or even suicide, if a soldiers mental condition has worn away significantly. Such conditions can be damaging to an army.
But Revan does have options. Trying to wait out Traya could give him victory, but it could also destroy him. All Traya has to do is have her assassins pose a threat and the morale of Revan's forces will degrade significantly. This creates an opening for Traya. The only real threat to her Sith now would be the Jedi, and we know how effective assassins are against Jedi.
Revan's only option is to strike Malachor quick and hard, or prolong the suffering of his men. If he attacks Malachor, he will lose. Which brings us to this question: How does Revan win?
Not easy to answer. Attacking Malachor is foolish, and waiting Traya out will hurt his army moreso. The best thing to do is not fight. Draw her out and strike when she is not on Malachor. In this case, the decision by the Jedi Council to avoid fighting the Mandalorians is the best choice. Draw out the assassins and defeat them as they come, slowly wearing down Traya's forces until she is forced to send in the Sith Lords. Eventually, Traya will either give up or empty Malachor's Academy in an effort to win. Then Revan can strike.
But I think you also underestimate the power of the Force. Simply starving Traya and her forces would not work. The Force can sustain a being for any amount of time should they choose so. Traya could play the waiting game just as effectively.