You can do few things:
Choice one, you can apply patch to both servers and remove Xsyon from Steam Early Access, and hope for population increase.
Choice two, You can separate group oriented "war server" which is meant for a group oriented players and allow other play-styles, like, solo, and casuals, on peace server, which from business perspective is more logical.
Why do you think most people are playing on PVE server? because most people are choosing PVE over PVP and since you placed restrictions on PVE server, only few players are actually play on it, group oriented players supposed to be on war server not peace server.
You don't realize this but you actually causing war server to stay empty.
You don't have resources for another server Xsyon but you can use what you have at your disposal, you have War server and Peace server you could use that to your advantage, keep War server as a Group Oriented server and Remove Restrictions from current Peace Server.
And when you have enough support you could always hire more help or even add more servers.
One more thing you can do, is a complete wipe, at least for Peace server, people got stacked millions of dollars and keep senseless prises at the trade market, which they looted from abandoned tribes "easy money", and are unfair advantage over everyone else.
Reason I wanted revs on scrap piles, because when population start getting larger you will have hunting problems, all the small and medium creatures are going to be exterminated from existence.