Pull apart basement wall to find first two. Your floorplan is different than mine, look for access panel on wet wall between sink and half bath. You might be able to explore /locate before cutting flaps.
If cutting flap on underbelly, 3 side hinge to front. Use Gorilla tape to close up. Regular duct tape will last about 3 days.
Front (Birdseye view)
Valve/ GT1 BT1/Valve (this one is right under first step next to vacuum)
Valves (plumbed out to front of tanks)
Doug & Tiffany
2016 F-350 Platinum DRW
2010 Harley Davidson FLHTK (Ultra Limited)
2015 Voltage 3605