Im sure it has been discused before but just offering up my STL and results if anyone is interested in this dual MFDs for your FA18-C : I used double sided tape to mount the face plate and MFDs enjoy lmk if you need help .
My setup is 2 1920x1080P monitors and a the 3rd being the one linked below.
Screen : https://www.amazon.com/dp/B0B87X5CDV?ref=ppx_yo2ov_dt_b_product_details&th=1
MFDS : https://www.amazon.com/dp/B002HH9TRY?psc=1&ref=ppx_yo2ov_dt_b_product_details
STL , tool for screen position and Lua included in Zip file below.
Dual Cougar MFD.zip