Dotted Barlines in odd meter

I have a piece in 7/4. The rhythm is consistently 123, 1234 throughout. I KNOW I could alternate bars between 3/4 and 4/4 but that will look very cluttery. I would prefer to just indicate 7/4 at the beginning, then help the musician out by having a dotted bar line after beat 3 of every measure. I've seen that done before. But it only goes between existing measures not inside one.