In my experience those lists don't need too much time to build up, and it's always harder to shut down their production mechanics than to get around the whole problem anyways. As you said, grow lists tend to keep close together, so the best idea is perhaps to capitalize on that: you can use all the open space you're left with, and once they spread out, attack them one by one with everything you have. Colette excels in that, also Marcus has a good chance to win by VPs, with matching speed and possibly some serious black blood immunity (silurids, waldgeist, KJ).
I never fielded Ramos vs these kind of neverborn lists and I can be seriously wrong, but your way seems to me like "lets beat them in their own game", which isn't too tempting. But if you want/have to play Ramos, probably your tactics is the best one to follow...
Side note: I must be the only one on this planet, but I don't find gunsmith to be terribly effective vs things like nephilim. They are pretty accurate for sure, but they seldom have the chance to attack the same target two times a turn. Even then, 1. the trigger is more than dubious to count on, 2. without the trigger, you can have tons of positive flips, but you still have the 1/3/4 damage code, practically 1/2/3 because you've chosen wooden bullets, not armor piercing ones. The red joker is nice to flip/cheat in once in a while, still not something to count on regularly.