I am pretty sure that a ACW era balloon is available from Fiddlers Green. You might have to recolor it.
Here is a model of the balloon barge. The model was on display at Mariner's Museum
https://a5cdad55-a-62cb3a1a-s-sites..../mariners7.jpg
Here is another barge model, this model has propeller which is incorrect since the barge was not powered
https://www.modelshipmaster.com/prod...rke-Custis.htm
I also have doubts about the model hulls, which don't look particularly barge like.
This is a short video of a model late 19th c. barge
https://www.youtube.com/watch?v=pqvp...ature=youtu.be
and a picture
https://i.pinimg.com/originals/0c/55...380bb7d319.jpg
Here is link to picture of the gas generators inflating a Lowe Balloon
https://warfarehistorynetwork.com/20...balloon-corps/