Thats a good idea, I would have a 20 page plan
Overview - what the business is set to do also known as Executive summary
Finances - upfront/startup costs, ongoing costs, minimum amount of risk capital to be a trader full time given the strategy you employ.
How will you start trading at a level that you will need in order to be a full time trader- savings, loans, partners, etc, working as a subcontractor (prop), etc.
Cashflow- how much money do you estimate the strategies will generate over say 1-3 mth period, annually, etc..
Strategy - Overview of current strategy, skills, returns generated already or in simulation, etc, then consider Growth, Hiring, Outsourcing, Maintaining edges, identifying new opportunities,
In this environment its more critical to have a business plan that describes explicitly your role and path to profitability, avoid technical things like how you trade.
Spend time describing differentiation from other Market players (other traders, market makers, etc) and whether the edge is sustainable over 1,5,10 years.
Their are a few book I'd recommend if you are going the systematic route - These books will make it easier to explain on the business plan the technology side of your trading with risk management, procedures for implementing complex systems, etc:
Inside the Black Box - Rishi Narang
Quality Money Management: Process Engineering and Best Practices for Systematic Trading and Investment
by Benjamin Van Vliet
Ernest Chan - Quantitative Trading