Excellent point. And perhaps even more glad in 30 years. A lot of the tax you will pay is Canada Pension. CPP is all the retirement most Canadians will ever have. Don't cheat yourself out of it.
CRA rarely audits small proprietorships. We have a self reporting tax system, and they're usually not eager to hassle taxpayers and discourage voluntary compliance. But keep your receipts! Hotels, flights, internet, cell phone, car expenses, lingerie *probably*. If CRA asks for receipts and you don't have them they can deny the expense.
The industry code isn't something CRA cares much about. Just about anything will do for filing.