Oke got couple up here and maybe even one question.
Suggestions.
1. Make it so you cannot oversell a Proxmox server. VPS module will always just drop the next client on the least loaded machine. This is fine, but when you are selling "true" packets, you may not oversell!
Add a point based system. Give a server points. Like a machine with 16core's you give 16 points. For your packages you sell you give 1 point per CPU that is contained in the pack. a 1 Core pack = 1Point. A 4 Core pack is 4 points.
Now you can make it so that Proxmox VPS will see if the server is fully sold or not!
2. Auto removal of servers. When a client is not a client anymore or if the order got removed, the modules should remove the created VM + all created backups of that VM. Or at least rename the VM to something like [Removed order]
So its easyer to clean out old proxmox VM's from long gone clients.
3. Multiple drives ? In our case we use the HDD's on our VPS machines as the fast arrays. But we also have "slower" large file clusters. It would be nice to sell space on the file clusters inside the VPS package, but separate from your primary storage.