Not simplest but easiest way developping 70mm film
Jobo CPA2 or CPP or CPE2 rotatingmachine to take up 2820 testdrum(smallest tank).
2517 70mm reel (172cm film lenght), of course one can use multiple reels in 25xx-tanks but i dont want to risk more than one film...
It so easy loading the reel and using the machine with lift.
But maybe you are right doing fully manual. Power-failure could be catastrophic.
cutting down 70mm film after shooting is another option to avoid 70mm-developping. A manual cutting machine would be nice.