We plant soybeans with the double hole plates. We actually countersunk the inside hole to help hold the beans better. I've never planted pinto beans before but judging from the pics I've seen, they are longated a bit.  I think in your case the trick would be to get them into the slot in the right orientation. If you drilled a hole and the bean doesn't cover it because it's out of position, you will have alot more air loss. You may not have enough air to hold the bean at all. You would need a big hyd pump to get enough RPM to the fan. FYI, we ran our fan at 3500 RPM with soybeans. I wouldn't want any less than that.  I would try just one disk and see how it goes. Try it at home by taking the meter chain off and turning it by hand with a wrench. That way you get a good look at how it behaves.