"pretty much an optimal way".
There is usually some misconfiguration somewhere that goes overlooked. Happens to the best of us :-)
What is your opinion (or others' if they'd like to chime in)? If you enjoy running your own, are there any guides in particular that you'd recommend? Does the future of email look even more prohibitively complex for self-hosting?
Following a guide to setup a basic email service is quite easy to do, but after a while the lack of proper implementation and maintenance of the standards will start to cause deliverability issues. Those are frustrating and most end up writing a long rant on why Google is evil because their email ended up in spam. When in fact, it usually is a misconfiguration, but those can be really hard to detect.
IMO there is still great satisfaction in running any internet service yourself. But, if you rely on this service to work, it just no longer makes financial sense to do so.
It takes resources to keep any internet service running correctly. Even the simple stuff can quickly get overlooked, I have seen so many self-hosted email servers that have expired certificates (like with the domain of the OP) or lack support for any of the modern security extensions such as DMARC or MTA-STS.
For most businesses my recommendation is not to run it yourself. Like you wouldn't run your own DNS service anymore. Of course it can be done, and in some cases it makes sense to run stuff yourself (usually when operating at a very large scale). But it almost always makes more financial sense to use a hosted email solution.
We haven't written a guide (yet) on setting up an email server with all the bells and whistles. But if you want to read more on all the email security standards, have a look here: https://www.mailhardener.com/kb/
For delivery, if you are really just using it for personal use a mailgun or sendgrid account can allow you to handle most delivery issues, while still handling inbound.
Which still leaves the other side, actually dealing with inbound mail issues which is just painful with either too much or too little filtering. The likes of google and MS have teams of brilliant people to handle dealing with spam, and despite some little guys caught in the middle, is still far better than I could ever do on my own.
In the end, if you want a career in IT, or find it interesting, I'd say go for it. I've often thought about building my own end to end open-source mail service aimed at ease of administration. If I was ever rich enough to not have to work, that's one of the things I'd probably do after a few months off.
I'd suggest starting with a secondary domain and using Mail-In-A-Box on a VPS or smaller Cloud host. It's a decent starting point, and there are many other options. One of my favorites is SmarterMail (commercial, windows only though). I also ran a BBS for a number of years using Synchronet, which does email/pop/smtop and even nntp for group messages. I did have it configured with SendGrid at the time for outbound for a while, which handled delivery issues for me.
You will have headaches if you take it seriously and/or use it as a primary service without using a delivery service like MailGun or SendGrid, and even then you probably will have other headaches. My point isn't really do discourage so much as let people have a more realistic understanding. The issues the OP has are real. However, there is so much junk from bad actors that the well is poison.
Please make your substantive points more thoughtfully.
What sort of config do you require from the OP? Their domain name is public and uncensored right in the top of the post. Their configuration has been cross-checked by many people so far. A lot of folks claimed that it has issues (like a `?all` in SPF, or `p=none` in DMARC, or some other nonsense that any spammer would easily get right), but those issues have been rebuked as not being significant to the issue at stake, plus, there's absolutely no confirmation that fixing these "issues" would resolve the problem, either.