This only work with low level bases. A high lvl base that has AA gun level maxed out, all units in the base will have additional +3 grid range, making this method useless.
uhhh bro it doesnt work like that. the enemy arty will always hit no matter what side of base but since it was a rocket launcher it has a lower range than your arty so they cant attack you
as you said now it's doesn't matter from which side you come, but up to lvl30 this tactic works perfectly good, and if you have maxed Antonia it will also work with lvl31 base