The Body For Life book suggests an off day in its routine where you can eat whatever you want. It suggests that you should do your grocery shopping at the end of that day because you will be far less tempted to bring home unhealthy snacks. Your diet doesnt contain the intense exercise of Body For Life, but perhaps a minor version of the off day and then buy groceries for the week would work for you.
I offer you a counter-proposal. I’ll eat “whatever I want” for 4 days and then eat “responsibly” for the rest of the month.