Arrrrgh!
I only use my impact to remove the lugs, never to tighten, and I always tighten lug nuts according to spec with a good torque wrench and using a three stage star process.
I think you just found the root cause of the problem.
"EVA'BODY KNOWS" using an impact wrench to tighten lug nuts is A Very Bad Idea (tm).
That is one of the few "Eva'body knows" nuggets of wisdom with which I agree.
(There are others, but they are few.)
What "Eva'body" DOESN'T know is that there is one condition in which using an impact wrench is NOT advised to REMOVE lug nuts - soft lug bolts (studs).
On a Main Battle Tank, you use an impact wrench for everything, because those bolts are over-specced and super hard (the steel, not the effort).
On bolts (studs) of lower hardness, using an impact wrench to remove a lug nut can stretch that lug stud on initial impact enough to stretch it out of spec, due to the increased torque necessary to break the nut loose.
An impact wrench just slams that nut loose and it won't loosen fast enough to keep from stretching the stud.
That means, when you re-use the stud, the recommended torque is too much and you stretch the stud too far in its now-weakened condition.
Of course, this also means you can't clamp the nut to the bolt tight enough to reach spec, resulting in a loose lug nut.
You won't be able to spin it with your fingers (I hope!), but it will not ever reach proper clamping force.
Note this only applies to soft steel bolts.
Super hard bolts will laugh at you, as you try to get them to proper clamping torque, puny human.
I have not seen any really hardened studs on travel trailers.
Looking at the suspensions on my travel trailers, with the crappy shackles, bearings, bushings and equalizers, I am convinced the lug studs are the same level of quality - i.e., barely up to the task.
Betcha a doughnut and a cup of coffee those lug studs on our trailers are soft.
Before you take that bet, consider that it takes only 100 ft-lbs of torque to stretch that lug bolt to its proper clamping pressure when it is in pristine condition.
Harder studs would take a LOT more torque to clamp, properly.
Moral of the epistle?
Don't use an impact wrench ANYWHERE on a travel trailer.
Breaker bars are your friends...
Stay safe.