I got tired of messing with T-bird years ago. Not that its a bad finish...But there are better products that stay clear and are just as durable, for a lot less cost.
I'd recommend finding an auto clear coating that is user friendly. They have flattening agents for that material too, but you are right.... it's a pain in the arse and comes out different every time you use it... I got introduced to a material called "Euroclear" made by Pro performance products. 4:1 , med activator, no reducer.
I gave that flattening agent stuff up too and just use a high solids clear gloss, and use air pressure and flow rates to create a very fine matte finish that comes out satin, low reflective finish. (HVLP 1.4 tip , 30 psi @ 10-12'' wide fan , low volume) It's kind of a learning curve too, but comes out looking nice, and stays clear without yellowing like epoxy clear coating. Arlo