I'll probably get a few "sighs" and likely some "heads shaking" over this comment, but here goes:
Well, as long as you're hearing something behind you "squeaking" you can at least be fairly assured that the trailer is still there and all 4 wheels are intact and rolling. It's the "screeching of rubber on pavement" that's a dead give-away that a wheel is locked up and if there's no noise, or only 1/2 the noise that's normal, check to see if you lost an axle.....
Really though, the squeaks and groans of the suspension pretty much comes from putting the "bare minimum" under a trailer that's "almost too heavy" and the trailer is "gonna complain" about that.....
Same happens with a tow vehicle with a 7200 pound GVW when you load it up to 7200 pounds and head to the mountains.... Some parts are going to be significantly more loud than they are when it's almost empty and you're "grocery shopping"....