How we did soybeans with a JD 4 x 38 planter. Was we did get the radial bean meters. They will pay for themselves in just a few times of being used. You can usually find four used ones on line or your local dealer may have some. Put a want ad on Graigslist.
Then the extra weight in the insecticide box should be all you need if you are only going to be no-tilling this one time. If you plant to keep doing it then buy a Shoup kit with the heavy down pressure springs. They are adjustable too.
As for row spacing. We would double plant the field. we tried splitting the rows the first year and found it was a real PIA an you ended up running on an entire row at times and making it germinate unevenly. I even made a hitch that was offset. It made turning the one way a real pain. So what we did after that was to just plant the field once like you would corn. Then just cross the rows the second time at an angle. Usually my fields are never square. So plant from one side the first time and chose a different side that makes the rows cross to follow the second time.
The checked planting has worked out well. It had some unexpected benefits. 1) It helps to keep the field from eroding. The water hits a row every 38 inches in any direction.
2) The beans feed into the grain head more evenly then in straight rows. The whole sickle bar is cutting not just the few over the row. The beans don't seem to pile up in the one spot as bad.
I sold my wide row planter to a friend five years ago. I now have a split row 15 inch planter. I like it and we are planting more beans so double planting them would be a pain. The friend still just double plants his beans. He averaged 61 bushels this year. So it does work fairly well.