[Carl n Susan]

ODS = off door side The RV folks like this definition but the auto industry uses it to designate the driver side. To me "curb" or "street" side is more definitive.

Yes there should be another handle along the frame akin to the 2nd black tank handle you found. They do like to hide them (sometimes even between the wheels). Hopefully the handle has not come off. That makes it more difficult to locate.