Catrike makes a “frame bag” which looks similar to this bag but as you see this mounts to the seat back and does not require a frame to fit into. That means it will fit various brands and models of trikes. Smoky Mtn Saddlebag Max as it is called offers quite a bit of storage space. They have a Facebook page. Please note that this bag is not waterproof.
Don’t ask me why, but they call this one their black model (makes no sense to me) …
And this one they call blue on black (makes sense to me) …
Poweron Cycling sells this bag for $65. Their shipping charge is $13 to my address. Other well know online stores offer it as well … all for $65. Utah Trikes shipping charge is $11. Amlings Cycle shipping charge is $10.
KEEP ON TRIKIN’
Tadpole Rider 
I don’t have the anwer to your question. Try contacting someone who sells them. Your other question is clearly answered in the article as I showed the price including the shipping cost.
The pack looks interesting as a rack with saddle bags / i have a Performer tadpole that folds, do you think it would fit and about how much are they?
Have a Good HEALTHY Day,
John
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