There is a vent hose that doubles as the overflow...it's supposed to run from the tank up to the fill area to a small round screen there. For whatever reason many FR trailers leave this hose off - so there is nothing to prevent critter infestation, road salt or crap from kicking up in there and a full tank will 'pee' on the road as you drive and the water sloshes around.
It's on the list of things I'll be fixing after the season. I can run a hose myself fairly easily, just need to 'drill' a hole in the foam used to fill the hole that all the other hoses run through in my TT under the bath vanity. YMMV
Jill & Chris, Wills (14) Evie (11) & Toby our collie (5)
2011 Grey Wolf 28BH
2013 Chevy K1500 Crew w/ Reese StraitLine Dual Cam
Nights camped 2011: 11 2012: 18 2013: 12 2014: 12 2015: 13 2016: 3