I do similar with our 5th wheel.
1/4 cup of bleach in the end of the hose.
Stick the hose into the gravity fill port.
Run water until it is coming out the vent.
Pressurize with the pump
Open the hot water bypass valves (make sure the anode is back in)
Open the furthest tap from the pump an wait till you smell chlorine
Close and work your way back to the pump using the same for all faucets (including the outside shower!)
Don't forget to pop the screen from city water hose fitting and jiggle the check valve till chlorine smell comes out (won't take long).
Lou and Laura with Bella - German Short Hair Pointer
2008 GMC Sierra 2500HD Crewcab SB Allison Duramax
2010 Flagstaff 8526RLWS - Superglide 3300
HAM CALLSIGN - KC3FFW