So, is there any way to complete this quest without going along with Jaree-Ra's plan?

Several different NPCs expressed a dislike for the Argonian but was only missing proof to get rid of him with.

I previously did Ahtar's (the Solitude executioner/jailer) quest that took me to Broken Oar Grotto to kill the leader of the Marauders. I found a note describing Jaree-Ra's plan and it also said he needed to find a scapegoat. But there's no one who will take it.

Bah. Wiki doesn't give any clues about an alternate route for this quest.
Maybe I can find him at the docks and just kill him without doing the quest.
Since that's the overall outcome anyway (and with no reward)

I'm a little mad at this quests too, he practically screams "IT'S A SETUP" when he discusses his plans.

Wish i could just cancel it :/

Bah. And then I go out of my way to stalk him at night until he's alone.
And he's [censored] essential Bleh!

No, you have got to go along with it. But trust me, by the end of the quest you will have done everyone in Solitude a large favor. So in a way it is worth it. It's frustrating though that your character has to be a low-life theif to be interested in and begin this quest.

I also hated this one, even though its really obvious that its just a freaking setup you still have to do it. My character isn't dumb?!