JKT
If it was me, I think I' d go ahead and get the 50lb bag anyhow. It will be cheaper. 8lb per acre will work, when I did my plot (which is only about 1/2 acre) I did about 6lbs...which is more than they suggest. It worked out fine. If I was planting 4 acres, I' d probably use most of the 50lb bag anyhow...and save some to overseed with in the spring if you get any areas that don' t take well...but that' s me. There are alot of other folks that have used IWC and on bigger plots, so they may be able to give you some better input. I think your success(no matter how much seed per acre) really depends on how well your plot is prepped and how good of soil contact you get(and rain of course). If you can get the seed pressed into the soil, rather than covered...it will do better. Should be a nice plot, you will be happy!

FH, you' re the big clover plot master...tell him what would be best.