Personally I use 5 waves in the support trains. Thinning the troops too much isn't really as much of a problem as it at first seems, since the troops that don't make it in on time can be cancelled and resent later at a different troop speed.
Also, its 4 chances per village, not 3. You even listed the 4 troop speeds
Another tip is to have 5sw/hc/cats in O vils as well so that if you have to resort to sniping with lc, you get multiple tries at ram/cat, sword, axe, hc and lc speed simply by accompanying each wave of lc with a single unit of the appropriate type.