Here's the underseat view from 2B (739) LAX-SFO on 11/07/17 - when I placed my feet forward under 1B, the top of my foot contacted "le sac de vest"; without getting down on hands and knees to take the shot but with the contact experience with my food, I'd estimate about 4 inches of clearance between the carpet and the bottom of "le sac":
Similar two shots for 3A (738) BOS-IAD also on 11/07/17 - there's even less space between the floor and the bottom of "le sac" as the positioning of my right shoe shows:
Two additional shots from my EWR-BOS segment (738) on 11/10/17 sitting this time on the other side of the plane in 2F - there was even less clearance than the other two sets of shots:
David