No one I have ever done business with would accept a bank statement as proof of income. I could make $20K a year and have two bank accounts and transfer money back and forth to make it look like I made 10 times that by just showing them one account.
I'm incorporated and I've always showed my income tax returns as proof of income. If you don't have then, they're lost, you haven't filed, etc. you have bigger problems than just showing proof of income
