You build the most stadium you can afford for SEC weekends and other top-end matchups including Regionals and Supers. You sell as many season tickets as you possibly can, and maybe still have a little seated inventory remaining for one-off sales for donors that are non season ticket holders.
There will be empty seats for midweek games and lesser matchups. Use the fill-in policy and give your tickets to Schloss policy to make sure all the good seats are occupied, and the additional seating in the outfield and down the base lines will go unused... -- why does this matter? I personally think people need to let this particular thing go as a non-issue.
Are folks super upset when the buy-in games at Kyle are not 100% full? Not even in the slightest. Those season tickets still sold right?
Are we stoked that we can cram in 102K+ for Bama, tu, LSU, etc? Absolutely.
Build it. and they will come.
ETA: no this isn't me saying 16K; I think 10-12K is where we land.