This is simple… any modern RV trailer built today has inadequate chassis under them, and it doesn’t mater if it is built by Lippert, Dexter, or in-house… the frame rails have little structural integrity, the cross members even less… so little the frame rails must be cambered just to hold the weight of the box built on top of them without sagging…
To be marketable they need to be light weight, and for the manufactures they must be CHEAP…
Then most users overload, misuse, or abuse them far beyond their intended design… it wouldn’t matter if it is a 16 foot or a 36 foot trailer… they are all just barely capable of carrying the load they are rated for and then only if and when the load is distributed correctly… remember all the weight is being carried by just a few feet of the chassis near the center and the ball coupler at the very front…
Your use of the jacks is proof of this, but it impossible to say that is the cause of your problem… its fair to say it didn’t help it… chances are good there was some damage done before… your door sticking is a sign, but it was done under static conditions without any of the dynamic stress caused by misuse and bad physical load distribution while in motion…
I would suggest you have someone very qualified inspect your frame… how you find that someone is the golden question… most likely that won’t be a dealer, and many weld shops are more interested in selling the job… but they are out there…
Good luck, I hope your problem turns out to be a minor inconvenience and not a major repair… it is something to be concerned about…
