I do use one domain with several subdomains (or simply a wildcard), that’s what I meant by the CNAME record(s). But I see that wasn’t completely clear from the post.
The setup time is not really a factor, more just the overhead of one tunnel and one Traefik instance vs multiple tunnels without Traefik. I might just do some basic “benchmarking” if you can call it that to see the CPU and (more realistically) memory impact.