I think the complexity of deontology makes it work as a moral system. It does not leave much room for loopholes that people can use to serve their own purposes. Doing the right thing is not always easy so systems developed on ethics are bound to not be easy as well. Often it goes against our gut reaction and what we want to do. It also expands on the golden rule of treating others as you would want to be treated. If you can not place yourself in the scenario or maxim then it is not moral.
While Kant thinks it is never moral to lie, I think with his tools it can be made moral. If you put lying in the maxim experiment then it is bound to be something that people do not want. Is it moral to lie if it will save an innocent person’s life? I am to lie about an innocent person’s location when they are being hunted. Everyone should do this. Imagine. Is it rational? Yes. Could I choose to live in a world where people do this? Yes I could. Looking at every decision like this would not be easy but as I said earlier, if it was easy then people go get away with doing immoral things using an ethical system.
Joey's Blog 
There are a number of current deontologists who agree with how you’ve discussed the lying problem in Kant–a new maxim that addresses certain circumstances needs to be used. The one thing to consider addressing, however, is Kant’s response to all this. I imagine he’d say you are forming a maxim on a consequence that you think will come about–saving a life. But we have no control over the future. Your maxim might be dutiful/moral but what if your choosing to lie still resulted in your friends death? He would say it would have been better to not have lied all along.
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