Just install a back flush device. There are a number of choices.
Dan-Retired California Firefighter/EMT
and Zoe the Wonder Dog(R.I.P.)
2016 PrimeTime TracerAIR 255, pushing a 2014 Ford F150 SCREW XTR 4x4 3.5 Ecoboost w/Max Tow Package
4pt Equal-i-zer WDH and 1828lbs of payload capacity
if it's anything like the 373qsi - and I imagine it is - look on the passenger side (side with the doors). And it's pretty much at eye level, not anywhere low... Yes you have to run the hose under the trailer, it's weird.