Did you have a complete list of requirements before you started? (It's not directly relevant, but the NAUI way is that the instructor can add whatever they see fit, but they have to have it specified before you begin.) If you didn't, well, it's a lesson to learn. Ask for a complete, written list of requirements now (so you can plan accordingly).
Whether or not it was "right", according to your agency or yourself, to have additional requirements, the simple fact is that without adequate documentation, you've painted yourself into a corner. Trying to reduce the requirements from whatever their current status may be is likely to only make you look "lazy" (which isn't the case at all, but that's how the cookie crumbles). On the other hand, no reasonable instructor would have a problem with you asking for specific written documentation, as that shows initiative and a desire to follow through to completion.
*Don't* be adversarial when requesting written documentation of his requirements, of course. This is the time to use the diplomacy skills that you should have been honing as part of leadership training. Tell him that you want to know where you are, and you want to be able to see where you're going and what you have in front of you. If he doesn't have something written, give him a few days, but do it specifically (eg. "That's okay. I don't need it tonight. I can drop by Tuesday after work and get it from you then, if that'd help.").
*Most* importantly, brand this situation in your head so you will remember it forever. When you lead trips or if you eventually become an instructor, remember how much you enjoyed having an ill-defined, ever-changing target frustrating you, and don't do the same thing to those who follow you.
