By Pat Forde The first rule of travel in the Great Plains Athletic Conference is that it’s all by bus. Forget charter planes at the NAIA level of college football; there are no planes at all unless the playoffs mandate it. Teams see a lot of Interstates 29 and 80 through South Dakota, Nebraska and Iowa in the GPAC. Ryan Grubb’s first bus ride as an assistant coach at the University of Sioux Falls, back in 2007, wound up in a park in Nebraska. “We stopped for the pregame meal, which was at a park, and we pulled the coolers out of the bus and had sandwiches before the game,” Grubb recalled. “So …