My 6250 GVWR ultra-lite trailer had a delivered weight of 5326 with full LP tanks leaving 924 for cargo. I know I'm close to my cargo limit when packed for travel even with an empty refrigerator an...
Not sure what you are asking....but obviously being 1000 lbs over weight (your estimate) is not good.
How old are the tires? - manufacturer date? My opinion, I think you have abused already suspect cheap (Chinese) tires and before you head out I'd replace them. I'm guessing that you already have that feeling, but are looking for someone to say that you are ok not doing so. I could be wrong, but as they say....I'm just sayin'.