You'll probably want to check it over very carefully starting with spring shackle bolts, shackles, u-bolts, axles for crystallation, cracking on axle housing near the outer wheel bearings and where it attaches to the pumpkin, etc...
The reason there are max GVWR is safety. Just because it didn't break with the load doesn't mean damage wasn't done and it's not about to break. Picture a paperclip. Bends easily once, and right back again. Try it a few times and it breaks. Metal crystalization is impossible to reverse, once it occurs it is just a waiting game until it breaks.
If you ever sell it you should probably tell the new owner what you've done so they know to look out for it too.
