I installed Proxmox to the nodes: sori, bori, and duri.
Installing Proxmox itself is too easy and too simple, so there's almost nothing to talk about. Kudos to Proxmox developers!
The only problem here is IP allocation, since Proxmox uses static IP addresses. Adding static leases is also very straightforward through OpenWRT's web interface. This information will be relayed into Dnsmasq, which will reserve the IPs AND resolve the hostnames automatically. Nice.
However, I realized that I cannot access the nodes from outside of my subnet. This reuiqres configuring DNS servers in both routers(jebi, nari) to refer to each other, and I'm gonna cover this in another log.
After installing Proxmox, I had to change APT sources and update the packages. That's pretty much it.