I just did a calculation and Nexstar could unload 21 smaller market VHF stations/clusters to Mission in exchange for WPIX and be under the cap. These are all markets without a Mission sister station. Out of the 21 stations the largest markets would be #32 New Haven–Hartford, CT #42 Harrisburg–Lancaster–Lebanon–York, PA and #43 Grand Rapids, MI.
The other markets would be Huntsville–Decatur, AL, Panama City, FL, Honolulu, HI, Champaign–Urbana–Springfield–Decatur, IL, Des Moines, IA, Sioux City, IA, Baton Rouge, LA, Lafayette, LA, Springfield, MA, Jackson, MS, Greenville–New Bern–Washington, NC, Bismarck, ND, Florence–Myrtle Beach, SC, Greenville–Spartanburg–Anderson, SC–Asheville, NC, Sioux Falls, SD, Johnson City–Kingsport, TN–Bristol, VA, Huntington–Charleston, WV, Wheeling, WV–Steubenville, OH.