I've spent the last few months researching this issue and have yet to find a solution. The main deterrent to what's available is that the ones I've found require mounting space on the inside wall just aft of the opening which is blocked by the bathroom module. I'm still working with one company that's looking for a solution for RV conversion companies. If one is found, it will not be cheap as the ones that I've found so far run about $2,500-$3,500. And then you have to get it installed.
Glass half full or half empty to an engineer is simply a glass that was over designed.
PM me for sale info on my 2011. SOLD!