Well let's see in 2005 North Dakota brought in 13 freshmen. They were:
Joe Finley (D)
Taylor Chorney (D)
Todd Alexander (D)
Zach Jones (D)
TK Oshie (F)
Ryan Martens (F)
Jonathon Toews (F)
Andrew Kozek (F)
Brad Miller (F and then played D later)
Ryan Duncan (F)
Matt Watkins (F)
Brain Lee (D)
Aaron Walski (G)
That team had 6 sophomores, 6 juniors, and 2 seniors. They went to 4 Frozen Fours in a row even though a number of players turned pro early. Not sure if this is even possible now with the transfer portal but we can hope?