Yes, you're right about the newspaper in Cincy. Dayton doesn't have a listing either. And yes, U Dayton has a 1-AA team, although their football attendance last year was about 3,000 average, so its not huge for football. So yes they are the home team in Dayton. Also, the average attendance difference between UCincy and Miami is about 10,000, going from 28,000 at UCincy to 18,000 at Miami U -- its 10,000, but not a huge difference.
But that southwest Ohio is an anglomeration of population centers. Between Cincinnati and Dayton is the satellite metro cities of Hamilton and Middletown. They are both located in Butler County, the same county as Hamilton and Middletown, as well as Oxford. Oxford is a town of 22,000 people, however, it is not simply just looking at it as they are located in a small town, "so that is their market". Its not like Ohio U being in Athens, OH, (1.5 hours from Columbus) which is a town the same size as Oxford.
Butler County has 350,000 people. The Hamilton newspaper does cover the Redhawks:
I don't think its unfortunate to be between two cities. The issues with small towns and big cities and college sports are odd with markets. Sometimes being in a small town nearby is just as advantageous as being in the city. Being in a small town at least 1 to 2 hours away and more is a disadvantage. But being within 1/2 hour away in the same metro area could be an advantage. Its kinda like the Big 12 taking the statewide schools in the smaller cities (College Station and Lubbock), except UT (Austin is a big city) as well as Waco for one of the 4 TX privates instead of the Big City teams in DFW and Houston (TCU, SMU, Rice, Houston). The big cities have a lot going on with the pro sports, and sometimes more than one university, that to be away from that a little, but yet close by near that population base has some advantages. As people have pointed out, Miami doesn't have a huge huge following, and small town location does have some disadvantages, but it can turn on a dime and for those same reasons may be some advantages to being in a small town 1/2 hour from 2 major cities and be in both of those metro markets (on the cusp).
As far as ECU, just like there is a 1-AA team in Dayton, there are 3 and maybe more that are in NC, that are similar types of universities to ECU. You have the HBCU of NC A & T in Winston-Salem. They averaged nearly 17,000 in attendance. Then you have Appallachian State and Western Carolina is the western part of North Carolina, which are both "Historic Normals", and similar institutions to ECU. Appallachian State averaged 12,000 fans last year and Western Carolina averages 7,000. Not huge by 1-A standards, but big for 1-AA. East Carolina averaged a little less than 30,000. I don't have the averages over a long period of time, though. But, what I am saying is that with the history of "Historic Normals" is that they were established as multiple colleges throughout the state, when they were established. Its sorda like if they don't follow UNC or NCSU, or the two major privates in NC, then they follow the regional "Normal" team, or its like "in addition to following ________U" they also follow the regional team. I know its possible it could be different in each state, but in Michigan, where we have 4 schools with a directional name, and 7 other schools that are also "Normal"-like, its like in Kalamazoo and SW Michigan there is heavy following of Western (which is the biggest of the 4 directionals as far as following), but people in Kalamazoo, or SW Michigan are also going to follow either U of M, MSU, and for that matter, there is also heavy, heavy following of Norte Dame in that part of the state ("Michiana"). However, there aren't that many Western Michigan fans around here. Sometimes people will follow EMU in addition to U of M and we even have MSU Spartan fans here in U of M's backyard. But not hardly any Western or Central fans. Maybe someone here can give anecdotal evidence that people in Asheville, NC (home of UNC Asheville) have a tendancy to follow ECU, in addition to UNC, and NCSU, but I don't see, from what I see in other states, much following outside of Eastern North Carolina, which probably means they don't get much following West of I-95. I could be wrong, though.