I'm not sure how much wiggle room you believe exists between the terms full and sold out but my first interpretation (when you initially posted) was that you were claiming all games in Memorial for a stretch ~40-45 years ago had 15k-16 people in the seats (and on the hill). I'm not sure if I would view attendance of 12k in Memorial as being full, but even if it would qualify as full, I'm very confident that you can count on one hand the number of games that had 12k or more during the time frame in question.
There were some games where 4,000 would have been a pretty generous assessment and sadly, 25% capacity (which 4k would be) pretty much qualifies as empty.
I understand how obsessed you are with our having an on campus stadium. I personally would love that myself but for us to have an on campus stadium that would be sufficient for what we want our football program to be is a bridge too far at the moment due to many reasons, the most important being that we will need success for a sustained period of time to rebuild the dedication of our fan base (hell, I just responded on the men's hoops board about the incessant complaining about the cupcake home games).
We will need patience (and sadly, as I'm pretty confident that you are in your early 60's as I am, it may take until we are both too old to appreciate it) for the things to fall into place before there would be sufficient movement among people in the fan base, the state and the state's government to want something like an on campus football stadium.