If you are worried, watch IRT Deadliest Roads.  They were driving big loaded trucks on some ricketty, crappy roads and bridges.

Unless it is a plank bridge with planks missing I am not worrying.  I am towing a popup that weighs 1,500#'s and my TV is probably 2,500#'s (guesstimate).  If a bridge can't support that weight, then it should be a footbridge. 

I have camped at 2 campgrounds where in their directions they have warned about the roads leading into the campground.  The West Chester KOA in PA stated that there was a sharp turn on a certain road and class A's and long trailers should avoid it.  Then I went to Ricketts Glenn and they said one road had an 18% grade and large trailers and RV's should avoid it.  I am sure the campground knows the roads around their property and will let you know to avoid certain hazards.  They certainly don't want to put you in harms way or have you ticked off from white knuckle driving when you arrive.