To answer the OP question, I'd say Probably Yes. Some of us have added airbags to the front springs and they help. Some have installed stiffer front springs and report those springs seem to help. So as a logical extension, Yes, these should help.
But first: Weigh it and adjust the tire pressure! Remember, 65-PSI in front tires matches the full 4600-pound rating of the 2007 and earlier E350/450 chassis. For any scale weight less than that, less than 65!
Then next: Check Alignment. CASTER at least 4.5L, 5.0R with CAMBER close to Zero and TOE slightly (like 1/8" or so) in.
Ford's Swing Axle (trademarked Twin-I-Beam) is capable, durable, and very suited to heavy loads while offering better comfort than a single I-Beam axle that's the Very Best for heavy load. BUT BUT, "Chassis Input" will cause the Twin-I-Beam to respond with a steering reaction. An unwanted one. That's why the Ford chassis calms down so much when we install HD Sway Bars or add a Rear Track Bar.
So, back to OP... If the Sumo part reduces front roll, it'll help with tracking. That said, Sway Bars aren't much more money, and are a proven upgrade.
If God's Your Co-Pilot Move Over, jd
2003 Jayco Escapade 31A on 2002 Ford E450 V10 4R100 218" WB