According to War of the Rebellion Naval records from Jan. 14, the Commodore had spent late '63 hunting a tannery and salt works on the Gulf Coast.
A letter from H.H. Bell to Farragut,
"Sir, I have the honor to transmit herewith communications from acting Master J.R. Hamilton, commander of the USS Commorore, and Acting Master Francis H. Grove. commanding the Coryphus. The Commodore and Coryphus have been doing a good service there in intercepting supplies for the rebels and destroying salt works and tanneries."

Both the Coryphus (a yacht used for marine assaults) and the Commodore took place in the assault in Bay St. Louis on Oct. 15, 1863 that destroyed the tannery.

Claiborne had written several times to Banks complaining about Henry Weston's salt works.
"If you could shell those places and seize the salt-boilers, we should get rid of the guerrillas and their sympathizers," Claiborne wrote."

Another account of Seward's story says that when they landed onshore in the convergence of a river or bayou with a eight to ten foot bank. I'm not sure this is possible in Louisiana because its all swamp from Fort Pike to Pearlington. There are two locations in Lakeshore where there is a steep bank that abuts the boyou inlet. Additionally, I have ruled out the Pearl River as the landing spot for a simple reason. The Union was seeking a salt operation----the Pearl River is a fresh water river, so there would not be a salt boiling operation on a fresh water river. Weston's salt operation was located about two miles away down the shore, where there is solid ground.
Apparently, there were confederate troops or cavalry in the area too, which I don't think would be milling around in Union-occupied Louisiana.

It's a compelling case that the action took place in Mississippi, I just cannot find the smoking gun. Thanks for all the help so far folks!