You have no security improvements? Of course you have.
This way you can use HPKP, do not have to change the key pin and just renew the cert every 90 days.
Do you always get a new certificate every 90 days??
You might probably just make to use a key size, which is large enough to be used around one year without having to worry about potential crack attempts by attackers with huge resources (aka nation-states).
Currently already 2048bit is considered secure enough, but if you want to make everything sure you can use 4096bit certs - also with LE.
This way it is IMO enough to change the certificate every year if you want to. That’s more than sufficient secure if you use a large enough key length.
And - to get back to HPKP - you only have to adjust the HPKP header once a year and can still benefit from an automated, free certificate service (LE) and - last but not least - the security improvident thanks to HPKP.
Besides this I also think @My1’s approach is interesting, but I’ll express this in another comment to stop putting everything in this one.