Good hopper rates? Cost of operation estimates?

Since farming has tightened up over the last couple years, I am thinking about putting an apportioned plate back on the truck and pulling a hopper around to make some money to cover some cost of living. I think it would pay better than a seasonal job for when the ground is frozen and after the crops are planted. I am located in Nebraska. I am willing to be out a few days at a time. I have run truck in the past pulling a bull rack, not really interested in that again. I know that it will take about 10k miles just to cover the cost of insurance and the plate. I have talked to a few freight brokers that specialize in bulk and hopper and have heard rates from 1.50 to 2.50 per mile. I have zero experience with commercial hauling with a hopper, so I have no idea what good rates are. One broker said hopper rates are a little lean right now, but expected things to improve after the first of the year. So what is considered to be a good rate in the current economy? Would anyone be willing to look over a spreadsheet and help me to estimate the cost of operation before I jump in? I need to be damn confident that this venture would be profitable before spending the money to get started. Thanks David