QTR-Quadtone RIP

I have an off-beat request: I'm trying to create, on transparency film, an image made up of dots, where the darker tones have the dots spaced closer together and the lighter tones have the dots spaced farther apart. 

I'm using this to create a photopolymer etching plate; for those unfamiliar with this, its probably most similar to screen printing, 

Using QTR, I'd be printing these at 720 or 1440 ppi. 

Here's the kicker: I'd like EACH DOT to be the same color, using about 94% magenta and 75% yellow ink. (The range of tones in my image file range from about 80% to white, so there is no pure black and no place in the image where the dots would totally fill up the space.)  

Could someone tell me what density and ink limit settings I'd need for both the magenta and yellow inks. 

I'm a novice to QTR. I asked this question a few years ago, but I'm not getting the results I need based on past advice. 

kind regards, david 

Best, David.