Doon, Iowa, ouch what a boring place. I lived up in that area for a year, it was mind numbing.
Your best bet is up in Souix Falls and the Iowa great lakes. Might find a few things down around Cherokee. Also look into storm lake, its a small college town.
Theres a ice cream plant in LeMars you could do a tour. There are a few small dirt tracks up in that area.
Lived in Iowa for 25 years and couldnt wait to leave, now after 4 yrs am looking to go back.