Well, from what I can grasp on this issue it sounds like a great idea that would restore Paxian activity whether for a month or however long. The main thing that comes to mind is all the work that will be needed to breath life into this idea. Two of the main issues appear to be dealing with reward and clan jumping.
1. As for the clan jumping I agree with Crimson Raven's proposal...
"Simple. Make war rewards only available for a period of time after the event ends; yet keep Negatus out during this time, allowing clan members to get any rewards. Then, take the items out, put them in the trophy room, and put Negatus back. May I also note that during events Negatus is always removed. Also, if the event is going to be a long one, give people a day or two when the event starts to change clans. This way, there will still be no clear leader, yet people are still granted freedom of movement. As always new members can always access Paxus to join a clan, and they just cannot leave during the event, unless at the very beginning."
2. Now for the reward I cannot say I'm too fond of the halving of defeated clans Z-tokens to be distributed to winning clans (as it has already been stated to perhaps cause discouragement in donating tokens and participation in the war). I do not think Z-tokens are a necessary reward (partly because it does help supply staff income) rather gold I suppose would make a more acceptable substitute relating to financial rewards if such a reward is highly craved. Personally, I favor the idea of clan shop improvements and depending on how long such a war should last (month(s) or somewhat permanent) could also affect the reward type (rewards relating to clans such as element susceptibility- winning clans are more resilient to losing clan's elements- would be almost unnecessary if the war was only to last for a month- this also depends on how long it would take for a clan to be defeated).
-Anyways, the idea of a war chest (clan items, gold, etc.) granted to victor clans who defeat the clan(s) they were at war with brings up the idea of rewarding passive clan members who wait for the rewards without participating. Honestly, if it was set up just as CR said for a limited time and they also set it up to the point where you had to complete a round (fight 2-4 monsters, just as though the war was still going on) before being able to access the war chest (just as they have been doing in past events) then I do not think the lack of participation factor would be much of a problem. I say that because to know if their clan has triumphed they would have to be participating and by the time the slackers realized the war chest for their clan has released items, gold, or whatever the time gap would have most likely closed. Now of course those on the forums would be notified, but then again they will most likely already be active. Well, those are only two issues out of the many more in need of discussion that I dared to scratch the surface on, but I believe if we are able to hammer out a good enough foundation for this it appears to hold great potential for Paxia’s future.