Instead of manufacturers having their models reviewed after they have been fully designed, several copies built, and begun shipping to dealers or otherwise offered for sale .... how about taking a ton of user inputs before beginning their design in the first place?
For instance - regarding access to the sewer drain - I can't imagine any experienced RV user providing feedback to an RV designer that "it is OK to have the sewer drain access up under the coach such that laying down on your back in the dirt/wet/snow is necessary to get at it "!!! That would be a ludicrous design and I wouldn't ever consider buying an RV built that way. Life's too short to mess with sewer drains - and a whole bunch of other dumb stuff in RV designs - any more than is absolutely necessary.