As someone who maintains my unit myself I have found the Cummins Quickserve Online to be helpful. As individual owners Cummins allows us to have accounts where a plethora of information is available. Early in my ownership of my Seneca I registered and received access. You need your engine serial number when you register. You can even add your generator to your account since it is a Cummins product.
The Quickserve Online web entry portal is here: https://quickserve.cummins.com/info/index.html
Using my account I saved the overall engine layout (attachment below), it shows the position of the oil filter on the right side of the engine. Of course in real life it is buried behind things, but I haven't had any trouble coming up from underneath to change mine.
Also per Quickserve my particular oil pan installed on my engine has a low capacity of 17 quarts and a high of 19. That is just the oil pan, not including what remains in the oil filter when you remove it. So I put 19 quarts back in mine at oil changes and it is well within the dipstick normal range.