If you're going to use "tide pods", I think the "general consensus" is to use about 1 cup of "blue Dawn" and 10 gallons of hot water in each tank, go for your ride, then flush the tanks thoroughly with hot water. DO NOT USE THE EVOO with the Dawn. Detergent is an emulsfier and will break down the EVOO, making it "useless"... Don't worry about Dawn making bubbles, they won't do the "dishwasher explosion" on you.
The black tank rinse (it's not a pressure wash) will help rinse the sidewalls and top of the black tank, but typically the spray valve won't do much other than "wet down the walls close to the spray head"... Don't expect "remarkable results and clean black tank walls" or you'll be disappointed.....
Once you have the tanks as clean as you want, then pour the EVOO into each tank to lubricate the rubber seals and plastic valve blade.
Here's a photo of the "water flow in a typical black tank spray head"...
I think everyone who has an RV has experienced "waste water behind the sewer cap" at one time or another. Most of us, after one experience, installed a "last chance valve" on the sewer terminal fitting and then put the cap on the last chance valve. That way, no "tank contents exploding onto you when you remove the cap"....
2015 F250 6.7l 4x4
2014 Cougar X Lite 27RKS