First off, the F-4 Phantom was designed with the assumption that it would only engage in BVR combat. In practice it didn't work out that way, but this was the intention. Furthermore, the M2000 first flew (I'm at work right now so I don't have access to my usual sources, but if wiki is correct) after both the F-14 and 15 had been introduced into service, both of which demonstrated far improved BVR capabilities. Whether the French were convinced of the importance of BVR may be a different matter, but they do seem to have made an effort at providing that option. Therefore saying that fox 3 wasn't a serious threat when the M2000 was introduced is a bit questionable.
Second, if you are at a disadvantage in a BVR fight and surface to air threats aren't an issue, turning off the radar, getting low to the ground, and getting your head outside the cockpit and on a swivel is probably your best option. Assuming you didn't cut your RWR for mystical reasons known only to yourself, that should give you some level of concealment while also warning you about aircraft running radar in the area. Furthermore RWR should also give you some warning about surface to air threats in the area so that you can steer clear of them.
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