New trailer spring advice req'd

[Maks]

We have a 2018 Montana 3790rd and after almost 30,000 miles it looks like I need to replace the suspension springs. A couple years ago I noticed some bad wear on one of the tires and it was eventually sourced to suspension misalignment due to a broken spring.
It was replaced in short order. Now 8,000 miles later, I notice that one side of the trailer rides a couple inches lower than the other. I checked underneath and saw that the three springs that were not replaced are flatter than the new one.
So I plan to replace all four with new springs, wet bolts and U-bolts.
My question is... Are springs available that are stronger than the standard 7000 lb axle springs and that would fit? I will freely admit that on occasion I run a bit overweight. (The 3790rd has lots of storage space....and with more space, more "stuff" seems to accumulate.)
Any feedback is appreciated.