This is what I’m doing as well. The nice thing about it is that it supports different sized drives in the same mergerfs mount and with snapraid, you just need to make sure one of your biggest drives is the parity drive. I’ve got 10 drives right now with 78TB usable in the mergerfs mount and two 14TB drives acting as parity. I’ve been able to build it up over the years and add slowly.
It sounds to me that for your specific use case, the tailscale free option would be a better match. You can self host it if you would like, using headscale (involves a little more work though). It’s basically like an orchestrator for wireguard tunnels.
I’m running tailscale on quite a few of my systems. I’ve configured the Grants (like advanced ACL’s) to allow for only specific services available from certain hosts while other hosts can act as exit nodes like a VPN egress. I’ve found it very useful for connecting families networks up so that I can assist with remote troubleshooting help and I’ve used it to reach back into my own network while traveling.
Tailscale would probably be easier for this. Install tailscale on the server and configure only that service available in the tailscale dashboard. I’ve used this method for ssh access to family members devices.
I’m sure you could run the same setup using headscale (tailscale self hosted), it would require a bit more setup though and dynamic dns would probably have to be working.
https://en.wikipedia.org/wiki/Aileen_Wuornos