Is the latency in the single digit ms range? Do you have a stable, redundant connection? Can you provide a 3rd vote? E.g.
Qdevice?
These questions are especially important if you want to use HA. Otherwise, two single nodes might be the better approach. In case you want to (live) migrate between them, you can do so manually via the CLI. But that call has a ton of parameters, and the Datacenter Manager (PDM, currently in alpha) is already a good option to trigger the remote migrations.
Besides that, the firewall config has a list of default ports that will be opened if the integrated firewall is used:
https://pve.proxmox.com/pve-docs/pve-admin-guide.html#pve_firewall_default_rules
That should help you for your question