Ok, if you decide to do it, you can use inexpensive single board computers, a standard build of nginx or Apache. Then it's not too difficult. Or rent a whole server. But renting a whole server is expensive. Learn to do it yourself. It's worth it.
That's kind of what I'm doing right now. Though not something like a pi, but kind of... I got a miniPC and am using that ISH. That got me interested in making my own little cloud. So my network is dumb and overly complicated. But I kind of wanted to so there would be virtually no possible way (sans state actors) that my tailnet would point to my home IP. The thing is, though, my miniPC at home is the headscale server. But I use my VPS +nginx to route traffic and conceal my homeIP.
I am REALLY REALLY REALLY out of my depth, though. The logic is easy, that's my thing. But networking fundamentals (nginx, iptables etc.) aren't my thing.
Sounds like you're headed in the right direction.
Right nos it's figuring out how to get any of my 3 exit-nodes working for tailscale, then all 3.