We have taken two trips since finishing treatment with the peg and Jevity with no problems. We have checked a box of cans (actually two boxes each weighing under 50 lbs) and carried a tote bage with a dozen cans, syringes, empty water bottles- to fill inside the terminal- and cups. We have a letter from the doctors with us but haven't needed it yet. The first time, at LAX, there was a line for medical issues and they just scooted us thru, the second time they took us to secondary inspection, swabbed the can lids and sent us on our way. No problems at all and if they would say anything my husband just lifts his shirt to show they the tube and tells them he can't eat any other way! No sweat...you'll be fine!
(fyi, if you check the TSA website it is stated that medical use liquids are exempt from the current rules!)