I was running a dozen or so Docker images in a LXC container in Proxmox.
Generally you really should run Docker images in a VM because they could break at any time.
Although a VM has more overhead and therefore might be slower, it is just not for certain that running Docker in a LXC container will always work like a VM will.
I found a github repo that will convert a LXC container to a qemu VM in Proxmox: