5rlyn I'm trying something similar. I deleted storage for CarrierConfig2, then downloaded Carrier Settings, and then reset mobile network settings (this is purely just guessing that maybe this helps Carrier Settings set the appropriate settings--but really I know nothing about how this stuff works). Then after that I uninstalled Messages, did the thing with the old version of Messages, updated to the new version and got reconnected to RCS. We'll see if it lasts any longer than 36 hours this time.
I did notice a couple things this time when I did the procedure with the old version of Messages. As happened the last time, I was immediately "connected" in the RCS settings, but Etouffee said false. I rebooted three times (that's what worked last time), but I was still getting false. Then I updated Messages in the play store and rebooted a forth time. Meanwhile, my VPN was on. But after the update and the forth reboot Etouffee finally said true and RCS started working again.
I conclude two things from this: 1) I'm starting to think that after RCS gets back to "connected" it just takes a few minutes for Etouffee to do its thing and show as true. For those of us who are incrediby impatient, we spend that time rebooting or phones maniacally. But perhaps after five minutes or so Etouffee would finally flip to true anyway. 2) I think disconnecting from your VPN to get reconnected to RCS and Etouffee probably is unnecessary. I guess it could depend on the VPN server you're connected to. But my first go around I got "connected" immediately with my VPN on and this time I got Etouffee true with my VPN on.