On ours, I found the filler hose actually went uphill from the outside fill port before heading down to the tank. Inside the trailer, I reached in and rigged up a strap to pull the “hump” down to allow gravity to work.
2018 JayFlight SLX 212QBW
1999 Ford F-250 Super Duty Lariat 7.3L PSD, 3.73
Transfer Flow 50 gal aux; Andersen WDH
😁 "If a man says he’ll fix something, he will. There’s no need to remind him every 6 months.