You still don’t mention how much work you expect the agent to do. What if you need to see dozens of houses and fall out of escrow a couple of times at no fault of the agent? Risk is not balanced for the independent agent with what you have proposed so far. Not in my opinion anyway.
I think 50% or more is a good rebate if you hand the agent a deal on a silver platter. If they know you well enough to be fairly certain you will perform, it might be a reasonable risk to offer you 50% including a more lengthy service as an agent fully engaged in helping you find a deal/place. I’d be thinking sliding scale beyond that. Of course then you could just dump them and reset the rebate potential with a new one.