Never heard of a foam marker using dish soap. What brand is it?
We use standard ag-type foamer such as Holloway. It recommends a 1:160 ratio. John Deere has a brand out now that is okay. I have seen the foam create a "burn" spot on a hot day --- especially if the foam is "runny".
I adapted a Simpson foam marker on a z-spray with a toggle below the fert controls. I only bump it on occasionally to avoid foaming everywhere.
I had it mounted and wired but have not actually used it yet. I got the twin 60 oz version. You can switch to left or right side plus you get a longer time between refills. Not sure the specifics as of yet. I'll let you know once I use it.
Let us know after your first run. The price is much better than other units I have experience with.
Here is a pic of how I attached mine. I used battery "j" bolts to secure to fertilizer tray. It converts in about one minute back to a JD gator for use on its boom. I ran just one hose under the belly instead of boom drops ---- that is all the plumbing I had on hand at the time. My problem is that this marker is a little too generous with foam and I prefer to toggle on/off in order to prevent an excessively visible trail. I prefer to draw as little attention as possible to my applications-- i am sure you know what I mean.
I can cover 3-5 acres between refills of its tank.