The tank and 6v6/5v5 has been heavily discussed, recently devs made a long devblog about it. I can kinda see where you're coming from, I think, but between balance/queue times/the average player (of which there tends to be more of when you're with 5 others instead of just 4) it seems to me like 1 tank works better in practice even though it struggles when compared to the ideal world+nostalgia goggles.
I was very pleasently ~~surprised~~ not disappointed by the monetization, like uncompleted weekly (battle pass -primary method of profression) challenges carry over, so in theory you can do all weekliesduring the last week if a battle pass. also aren't the new heroes available if you play just a few matches?
I don't understand what you mean with the content disappearing when you mount the virtiofs on the guest - isn't the mount empty when bound, untill the guest populates it?
Can you share what sync client+guest os you are using? if the client does "advanced" features like files on demand, then it might clash with virtiofs - this is where the details of which client/OS could be relevant, does it require local storage or support remote?
If guest os is windows, samba share it to the host. if guest os is linux, nfs will probably do. In both cases I would host the share on the client, unless the client specifically supports remote storage.
podman/docker seems to be the proper tool for you here, but a VM with the samba/nfs approach could be less hassle and less complicated, but somewhat bloaty. containers require some more tailoring but in theory is the right way to go.
Keep in mind that a screwup could be interpreted by the sync client as mass-deletes, so backups are important (as a rule of thumb, it always is, but especially for cloud hosted storage)