Options are always nice. I think most of these ideas are cool (well, the more sensible and practical fatigue-related ones, anyway). For the 50m furballers it would just exaggerate the already amusing effect of new planes being fed into the meat-grinder, gradually getting damaged, lower, and slower and also more tired than the opposition, and then being destroyed by the latest newcomers. I'd quite enjoy the amusement to be honest.
Either way, it's not a terribly difficult suggestion to plan a sensible implementation of, I just dread to think how anyone would arrive at any hard numbers for it. Have a little green bar at the bottom of the screen that depletes (slowly) but at a rate that varies exponentially depending upon how many Gs you are pulling, and gradually reduce the maximum stick force allowed to the pilot from its usual 50lbs and their blackout G-tolerance from its usual er...however many Gs it is (5?) - up to a reasonable point. Then for good measure, make it a difficulty option, because sometimes you just don't need the hassle, haha.
Splitter, I totally agree about 'leveling'. It's ruined several games or at least constituted an annoyance during gameplay. Especially in online games! Let the effects of player experience tell by allowing them to perform every action from the start, just make their successes dependent upon how good they are at doing so in the sense of planning and hand-to-eye coordination! All of these FPS games with 'levels' and 'feats' are just weird.