I see your line of thinking, but I believe it's more of the bigger guys not wanting to play ML than ML not scheduling up (also, 8 weeks are accounted for by their MAC schedule, so limitations are there from the jump). Honestly, if you're a decent D1 or D2, particularly if you have a lot of league commitments, why would you schedule a Marion Local? You risk a (likely) loss, but even if you do win, the Harbins from a D7 running the table may not be as rewarding as scheduling a (for example) solid, but not great, Cleveland Senate team that'll be 5-5 or 6-4. The system is FAR from perfect, and for now, the incentive isn't there for D1/D2 to play teams like ML. (FWIW, D1 Northmont, in 1997 and 1998, played D5 (and current ML MAC rival) Versailles and got shutout both times).
As for your second point, that is where being a bigger school in a bigger market, and the associated media coverage is an advantage. Let's face it, Mercer County isn't a media hotbed. The Glenville, Massillon, Ed's, Ignatius, and GCL types can schedule nationally because those are the size of programs that get the national media coverage; and it's why those kids tend to get the good college looks, fair or not. For as good as ML is, there probably aren't very many teams with their enrollment level that they could play nationally that have that kind of track record, and those that do are probably hard to find, because of the lack of press coverage.
And as a straight-up prognostication, I think ML would match up well with Winton Woods. In a hypothetical 7-game series (which would never happen in football), it goes 7.