Usually you do not have a static IP anyway. Sure you could probably backtrace the DHCP of your ISP to the date yout that IP got issued…But that is IMO a bit overly paranoid.
Though to be fair’ I don’t know why they don’t like VPNs for signups. Most likely to enforce IP based bans for not following rules or for entire banned countries.
If you don’t really care about the rules, just do it on signup but don’t connect US -> DE but instead US -> US. That way they may not care enough to enforce rules.
One tracker even mentioned that the rules are there. Some are strictly followed (like naming rules), while others are not followed as strictly.