We have a 2005 safari 25FB, named Lucy, that we have camped in for over 800 nights and have towed over 70,000 miles. Lucy's door operates pretty much the same way that you describe. It takes fairly significant force to make the door close securely.
We too had the same opinion about Lucy's door. Several years ago we had Lucy at Jackson Center. We discussed this issue with the service technician. He adjusted the door jamb pin out ever so slightly. Before he did this, he marked the pin's original position with a sharpie. The door did close easier. He told us that in many instances, doing this adjustment has caused the door to leak. He said that this is especially true of rear hinged doors like Lucy's. He showed us how to readjust the pin to its original position, in case we wanted to put it back.
Just as the technician had warned, the first on the road rain produced seepage. We adjusted the door back to its original position, where it remains today.
You sewer problem sounds interesting. I can't wait to hear more about it.
SuEllyn & Brian McCabe
WBCCI #3628 -- AIR #14872 -- TAC #FL-7
2015 FC 25' FB (Lucy) with HAHA
2005 Suburban 2500 Quadrasteer (Olivia) & 2011 Silverado 3500 (Fred) with Outfitter Truck Camper (Ethel)