I have heard that they plant a lot of SS in parts of Michigan with very high deer population. I had some soil tested and got a recommendation for 15T of sorghum silage vs. grain corn. The P&K needed was similar, but the N needed was much less for sorghum. Should go back and look at corn silage vs. sorghum silage.
I think the issue here is between poor drainage, light soils, and deer - - there is only about 1/3 of the farm ground that is well suited to traditional row crops. So you need to look at other options. I guesstimated it would cost, including land rent, $64/T dry matter to produce forage sorghum. Harvest would be extra.