Luke’s plan to rescue Han makes complete sense when you realize the reason his plan is so complex is because he’s going out of his way to not have to kill Jabba. Because that’s what Jedi do. Negotiate, not kill.

His first plan is to use the droids as a bargaining chip. Lando is planted there so he can get them out after Han is freed, and they lose nothing. That fails. So Leia’s sent in to free him, but she’s caught. Crap. So Luke has to go in himself. He calmly tries to negotiate with Jabba one last time, but he refuses. He knew about the Sarlacc, but not the Rancor, which is why he’s surprised by it. He planted the lightsaber in R2 in case he was gonna be thrown in the Sarlacc pit. Because otherwise they’d nab it off him when preparing to throw him in. And thus we get the sail barge scene.

Luke’s plan isn’t actually needlessly complicated, it’s just that we saw the worst possible scenario because Jabba is stubborn and insane.