I'd like to start off by saying that the "only able to send def to ally/confed" to prevent spiking is a great first step in the right direction. However, it also creates a new problem when it comes to chiefing.
Before that new rule, whenever chiefing important targets, especially when chiefing into someones cluster, most decent players would have def lined up to land right after the village was to be chiefed, along with merchants to feed the def. It was pretty common practise to avoid the original owner from rechiefing it straight afterwards, or trying to cat it down afterwards.
That strategy is no longer possible which is quite problematic is some cases. Sure, you could have last chief land with def so it stays in the village. But this doesn't fix the problem as you can't have merchants lined up to feed the def, and purely offensive players shouldn't have to be "forced" into needing to make def because of this change in the rules.
What I suggest is, being able to send reinforcements and merchants to anyone on the server, but if at the time of landing, the village is not part of senders alliance/confed, then they bounce and go back to the sender.
This both fixes the problem when it comes to chiefing while still rendering spiking impossible.