I'm pretty sure I don't need to give the background on the Robber Camps cutting waves issue.
Raise your hands if you've never sent your army to a Robber Camp and it returned home empty handed.
A simple solution mentioned by lua was to apply similar rules to those when you attack a Treasury. The only unit capable of stealing Treasures is the Hero.
So the idea is very simple and effective at the same time. Only hero can get stolen goods from Robber Camps.
This would limit players to attack 1 camp at the time avoiding the mess that happens server and server, regardless of the team I've seen it happen all over. So like you need 1k units to attack in siege mode you need your hero to attack Robber Camps .
I would also add that you should be able to clear the last wave 100% of the time to fasten the clearing process, therefore speeding up the re-spawn and avoid hurting the active players at the time.
There you go, waiting for this to be tested on the next TEST x5 to see the feedback
P.S.: I already see greedy people disliking this and diplomats saying that it's a matter of respect blablabla, it isn't.