Oops! For some reason I can't edit (continue) the previous message.
Anyway, I believe it is the total weight on axle assembly and the tires that is critical. If your axles/tires are rated at 3700 lbs, you are already overloading your rig by almost 700 lbs, or 19% of its stated capacity. This could go even higher without realizing it just by carrying a 'few more items' for the next trip.
As I stated, I am by no means the expert on this topic, but your own description leads to concern, or at the very least, confusion on my part.
Without the mathematical analysis (but YEARS of experience), Sawdust seems to be saying pretty much the same thing.
For the life of me, I can't understand why there should be ANY confusion in the industry over this important issue. But last year I was puzzled to realize how 'slippery' many of the local boat dealers were when I asked these questions. (None we CD dealers.)
I was trying to decipher the GVWR of my Ford Explorer. Then I would be standing in a boat yard, literally, pointing at a boat/trailer rig sitting there waiting to go out the door, and ask: "What does that weigh?" "Well, uh, I'm not quite sure . . . you could look it up in the specs . . . . Of course, it all depends on how you've got it loaded up . . . Some people carry everything but the kitchen sink . . . "
OK, let's assume we have all tanks filled 50%. YOU TELL ME how much a TYPICAL load with batteries, moderate food suppllies, tools, and fishing gear will weigh.
"Well, uh, everyone's different . . . . "
"OK, let's assume we have the tanks half full, two batteries, and TWO HUNDRED POUNDS of personal gear . . "
"Well, I don't really know . . "
"AAARRGHHH" HOW MUCH DOES THAT G--D--- RIG WEIGH?"
"Well, . . . . . "
Yeah, yeah, yeah, America is a litigious society, blah, blah, blah . . .
iggy