1) You have written a picture book.
2) The text of your picture book does not make complete sense without pictures (very common of course).
3) You can't draw.
What is the best way to present this as a submission so that all of your ideas are transferred? Assume that you include the complete text in a double spaced document complete with suggested page numbers.
a) Dummy book with the text in place and descriptions of potential illustrations?
b) Include an explanation or breakdown of your illustration ideas in the covering letter or separate document.
Exactly. But hold yourself back. Only include enough direction to make the text make sense. Extras are not appreciated. As I said not long ago, illustrators are half of the creative team—not a tool for the author's use. Sure, you have a vision for how your book will look. Open your mind to the idea that an actual artist will have a better one.
c) Find someone who can draw to illustrate your dummy book.
This is a bad, bad idea. Many of the people in slush send in their own illustrations in the belief that they might be in the running to illustrate their own book. Most of those people are at an artistic level so far from professional that this belief qualifies as loony-tunes. People that unrealistic give us serious pause.
I know, you're not one of them. But if you send in the best illustrations you can get done from the very small pool of illustrators you know and with the very low amount of money you can pay, those illustrations are going to look damned unprofessional. And you will run a very strong chance of being mistaken for one of the loony-tunes who think that level of illustration is acceptable.
Editors get plain old manuscript pages all the time. Here's the thing to remember: we have very good imaginations, and we do this for a living. We're good at visualizing. Give us a little credit.