Not the best picture, but this is where I have my 2 stage water filter system. It works well and is easy to remove to replace the filters. There is approx a 1 inch gap between the door when closed and where the hoses pass from the filter assembly to the trailer input fitting and also from shore water. I have said I was going to mount this filter assembly to the wall, but it rides nicely where it is and I just haven't bothered to do it.
Sorry for the rotated picture.
2006 GMC 2500HD CCSB 4x4 Duramax/Allison, Titan 52 gallon fuel tank, Prodigy Controller, B&W Companion Hitch
2010 Jayco Designer 35RLTS, Cummins/Onan RV QG 5500 EVAP, Progressive Industries EMS-PT50C, TST Systems 507 TPMS, RV Flex Armor Roof