I've also been hosting since before Gmail was a thing but have since set up new servers with new domains in disreputable subnets, and I haven't had any delivera

I've also been hosting since before Gmail was a thing but have since set up new servers with new domains in disreputable subnets, and I haven't had any deliverability issues. If you configure things right (SPF, DKIM) you won't have problems. This idea that self-hosted email is impossible is wildly overblown.