A big part of stealth is dictating strict flight paths, especially going into AD, which, in theory, gives them the opportunity to give that S-400 operator the best stealthy angle for the jet. Also, I don't think you're seeing drop tanks going into an area with S-400 operators, those F-22's are flying with a string of tanker support. The F-22's that are flying with drop tanks are on patrol missions domestically or are scrambled. But those jets are also likely already flying with radar reflectors, hiding their true stealth capabilities even without the drop tanks
Why would you want to run a strict flight path? This is what did in the F-117a over Serbia/Yugoslavia...
Then flying with a host of tankers. Gee, not another red flag to a crafty radar opeator...
The fact of the matter is, these operators on missile defense systems are getting craftier and craftier. Extending frequency wavelengths and other tools to again, not pin-point a 5G stealth fighter, but figure out that something unfriendly is there. Then from trajectory tracking it, narrow down that flight path to at least throw something up in the air at it and hope you get it.