I like this!
Do you have any info on the products you've used?
I've seen this lots on commercial tankers, but if you have any info on the specific parts that are compatible to the RV systems, that would be very helpful!
The second I saw the first picture I said "well, old style oil filter wrench". I say old style because cars I owned in the 70s and 80s allowed access to the filter with this wrench while everything I've owned in the last 30 years, no way. too much stuff gets in the way.
But good idea nonetheless.