Join Date: Feb 2007
Location: Spain + Germany
My Motorhome: Four Winds RV
Thanked 422 Times in 398 Posts
Have a look at your waste trap under the sinks, you may have little vents going up from them (purpose unknown), we have one under the wash basin in the bathroom which caused a stink while driving. I blocked it and solved the problem.
RVs are different from motorhomes in many respects. You may do better for answers on an RV site, though there are a few of us here.
Propaganda works best when those who are being manipulated are confident they are acting on their own free will.