I did this before saved covers were added, now I just sell the 144 and start a new one when I get the next cover (other than the three I use for DDQ (Storm, Magneto, and Hawkeye)).
Playing SCL 10, you don’t need 2* characters, and with almost all the 4s and all the 3s championed, you can easily do the Behemoth Burrito with a level 15 2*.