Just to close the loop on my comment on this post about wanting to upgrade springs on our 4 year old TT:
Since springs are only part of the problem, this morning I closed the deal on swapping our 3,500 lb Lippert axles for 5,000 lb Dexters. Finally found a non-RV shop 40 miles away that actually does this routinely and seems to know what they are doing. As part of the deal this guy keeps your old suspension/tires/wheels so the price was about 65% of what I expected. Plus, I already had budget approval to replace our 5 year old tires this spring anyway.
Our trip weight is 7,550 with 1,000 lbs tongue weight, so we are typically 400 lbs away from suspension (and braking) limits. This trailer only had 700 lbs of payload capacity when we bought it new. (Yeah, I didn't know to look at this when we were shopping).
The trailer guy crawled under it this morning and came out shaking his head, said the springs were flat and the axles were almost bowed in the opposite direction (and it was 400 lbs under trip weight this morning). He said, as we all know, that newer TT's come grossly under-axled and run right at the breaking point.
Parts will be here in 2 weeks and I'm excited! (I'm easily entertained). I have been weighing everything that goes in the trailer and run a spread sheet that calculates all the weights versus design limits. Worrying about breaking a spring or bending an axle has really sucked some of the enjoyment out of our longer trips.
DW gets extra credit for patience on her housewares weight budget. I told her today to go ahead and order that hot tub and I'll find a place to mount it on the trailer.
I wish I had done this a couple of years ago!