As mentioned, the first 3 pages should be easy to read and easy to digest. Don't get too technical in the front matter. You are setting the stage for the good stuff to come.
After you set up the proposal with a high level overview and context, you can and should get technical in the subsequent sections. As long as you adhere to good technical writing guidelines, this is where you demonstrate that you have the technical depth to get this project done.
This article builds on content developed by the Martin Trust Center for MIT Entrepreneurship for MIT's Orbit Knowledgebase and is licensed under CC BY-NC-SA 4.0.