Blue, I second Barrys advise on the P trap. DW was taking a shower on a recent trip, I happened to have my head in the basement doing something and heard water dripping where it shouldn't be. I pulled off the access panel and found the P trap was not only loose, it was mis-aligned. I completely took it apart, then reassembeld it straight, and that solved the problem.
2012 F350 Lariat Supercab DRW LWB Diesel
Reese Elite 18K - Trailair Triglide
2014 Sanibel 3500 - everything but the generator!