Two things about fronting with your own domain:
1. You have to own that domain forever, until or at least until you're 100% confident that an email intended for you will never be sent to that domain ever again. Even then, there are security risks with giving up the domain.
2. You give up some privacy. You can use mailbox aliases but it doesn't really matter if all the mailboxes are tied to a domain registered to your name and address.
1. A little money solves this. You can register for 10 years at a time. Any decent registrar will blow up your email near your domain’s renewal date regardless of renewal status.
2. Whois privacy solves this. Free from any decent registrar.
For (1) you can prepay i think up to 10 years? And every year you just prepay 1 year again and you will have 10 years to remember that you forgot to pay a domain registration bill.