Have not tried Blacktail's clear, but have used plenty of 2K Acrylic clear for Autos, which is what they are selling. I'm sure it's good stuff, depending on who packages it for them. The fumed silica they use for flatting agent can be used in any finish, but you would need to get it in the dry form.
I did not look at prices, but shipping all that hazmat crap must be expensive. You could probably find some decent 2K clear at a local Auto parts store that sells paint. Fumed silica in the dry state is common and cheap. I buy it locally from an auto body and paint store, 1lb= about a 3 gallon volume, which is enough to flatten many gallons of finish for about $15.
I'm always surprised more people don't use Auto clears. Not many finishes take as much abuse as a clear coat on a car, or are expected to protect such an expensive item.