Trains are a great rapid response measure if your opponent isn't magical nonsense. Even the best trains in the best circumstances are going to take hours to respond and unless they somehow manage to suffer a critical equipment failure for our benefit or decide to all get out and moon the locals as some sort of hazing ritual for the new recruits then I don't see them hanging around for that long... In the time-scales that we are looking at, the train is no better than a fixed installation, the only advantage is that it can be relocated so that they can't permanently map out our entire defence grid...
Guided missiles will most likely fail to knock them out of the sky, but at least there is maybe a chance there, and it has pretty good odds of doing enough damage to keep them on the ground if they decide to stand still down there. And if we are trading ten pilots for every hostile craft that we bring down then I think that we should consider it a cause for celebration. Sure, once we start reverse-engineering some goodies then we might be able to remotely match them in the air but for now we can expect to be out-ranged, out-armoured, out-ceilinged, out-manoeuvred, out-aimed, out-sighted, out-run, and out-lasted... The only reliable advantage we have is numbers and throwing cannon-fodder at a numerically-inferior-but-otherwise-superior opponent tends to have a very specific downside...
But Imma following the rule of "don't vote for your own stuff, because that way lies madness(and not the good kind). As for the revision? Umm, I guess I vote for mounting the R.D.F. on a train and providing the necessary additions(fixing its vulnerability to wind obviously, no point putting it on a train if it breaks whenever it moves...). It may not be able to respond in time to react to current threats, but reducing the enemy's ability to track our detection ability and being able to repair holes in our detection grid sounds nice. Also, it would sort of vaguely increase their coverage area if they are mobile(straight lines and stuff...), at least until the enemy adapt their flight-plans to account for it... I kind of hope that we can do it as a revision because we are revising it to be mobility-tolerant, putting it on a platform and dragging it along a rail-line is hopefully a bit of a freeby... But just upgrading its specifications to be more resistant to motion would be an upgrade to its resilience, so that seems like a win...
+1 "put the R.D.F. on a train as a revision"