Could you look to relocate were you put the main black tank flush connection in the storage compartment of at least the 350M? I not sure what the other compartment hookup areas look like, but on my 350M you have the black tank flush connection at the very top of the hookups. This is a problem area as water does drip from there as you are flushing the black tank and drips right down on top of the fresh water connection. This can cause cross-contamination with the fresh water system. I would like to have mine fixed as well, so that we don't inadvertently get sick from this.