Filters like these can be bought at Home Depot or Lowes and most any hardware store. I suspect Willis had to find a stud because if that bugger gets stuck, it takes alot of torque to undue.
I can see if you are able to travel with the trailer for 6 months or more a year that the issue of changing the filter would be a PITA. However, I have these sediment filters on most of my vacation rentals and those things only need to be changed every couple of months in the high occupancy periods and this for an entire house.
I will be lucky to actually use our Roo 30 days a year, so for me I will change the filter when we winterize it. I suspect FR does not anticipate the need to change the darn thing but once year at most, so they stick it out of the way...
Bob, Tonya and the kids
11 Rockwood Roo 233S
08 Grady White Seafarer 228
08 Tundra 5.7 liter 4x4 crew cab TRD limited
08 Toyota limited 4 Runner Iforce V8 full time 4WD, tow package