I don't know just how different the configuration is from ours to your rig, but I did everything from the bottom. Didn't remove anything. Just knelt on some cardboard, and reached up between the hitch and the lower part of the grille. I'm not very tall and had very little problem R & Ring the fuel filter. It was my first time, so I was really concerned I might have a problem with air in the fuel line. I got a suggestion from Cummins... take your time and fill the fuel filter with clean diesel pouring into the outsied filter holes, NOT the large center hole. Filling the filter that way only took a few minutes longer. I bumped the key two times and waited for several seconds each time and it started right up.
Hope this helps,
2003 34H Journey, 300 HP Cummins, 2000MH Allison, Demco "Excalibar" Tow Bar, BrakePro and Chevy HHR