Like Pete, I would generally recommend against SS spikes in wood ties, but I don't have any direct experience with the composite material Switch Crafers uses. Be interesting to find out how SS holds over time.
SwitchCrafters.com does offer insulated frogs, however with the addition of two insulated rail joiners on the two rails coming from the frog point and a micro-switch at the points end, you now have an insulated frog. SwitchCrafters does offer a water-proof micro-switch with installation for $17 on any of their switches. You may want to call them at 541-990-4455. Hope this helps out.