Stealth doesn't actually change the engagement distance significantly. Limited factor is still the no escape area of your armament.
Though smoking engines don't help you regarding the IR signature management.
Actually it does, you're not likely to get a "lock on" from 100 or even 50 nautical,, you're of necessity going to be a lot closer, and that is true whether your own aircraft is stealthy or 4Gen,,, so smoke is a very bad thing, real fighter pilots look for smoke, if the other guy engages burner and starts leaving a "plume" that's bad for him....
Real L/O aircraft are doing very well, in very real, dead serious Red Flags etc.. so stealth is indeed a game changer,,, to my knowledge, no one has claimed a kill on the F-22, or the F-35 at ANY significant distance, its always up close and by chance!