You just described teams from the Mac and Sun Belt. As for small venues...Idaho (16,000), UMass (17,000 when they don't play at Gillette). The only 2 under 20,000.
BSC has 6 teams that currently meet the 15k requirement ( UM, Sac St, PSU, MSU, WSU, NAU) and 2 over 20k (UM, Sac St). MVFC has just 2 teams under the 15k requirement (ISUb and USD), but only 1 over 20k (YSU). We are all FCS teams, why should we have 30,000 seat stadiums. NDSU wasn't selling out the dome in 2004, and UND wasn't selling out the Alerus in 2008. So what is your definition of terrible attendance? In 2013 both the MVFC and the BSC set conference records in total attendance.