@joshjosh asked for some charts to compare my concept of the FAXX with some relatively similar aircraft, and I got a set that aren't terrible. It's been a long time since I've fought with LibreOffice to spit out neat charts, so these are still uglier than I want.
As a reminder, my concept for FAXX is a 40,000lb empty aircraft with 28,000lbs internal fuel and 12,000lbs internal weapons capacity for an 80,000lb takeoff weight. This was based off of carrier limits, primarily the 55,000lb recovery limit talked about with Tomcats and the 6 Phoenix load. If the EMALs has enough horsepower to throw an aircraft over 90,000lbs, then we can assume 12k external weight plus full internal fuel, but I was originally assuming launching the planes with 16k of fuel onboard and tanking immediately after takeoff in the max-strike mode. But you'd absolutely have to drop the external ordnance to land back on the carrier if you were in "Beast Mode."
If you look at the loaded and empty weights, my idea isn't outrageous. The only really sketchy part of this is fitting 28,000lbs of fuel into the airframe. That's 5000lbs more fuel than F-111B or Su57, and both of them have a higher empty weight than my concept.
My current visual model is basically an extra-thicc Su57 with a bay ~55" wide by 25" deep between the engines in place of the existing tunnel, and weapons bays on the sides of the intakes instead of the weird armpit bays of the Su57. Probably tailless, and flying either a Lambda or a Delta wing.