I too was worried about the left side bias on our 337 which was 715# on the factory weigh sheet. I think this may be typical of this type of floor plan with the large kitchen slide on that side and seems to be a very popular style. I was told that the Correct Track system is installed on the camper for this reason.
I spoke with Lippert Components last year and they put me onto Sonny Dismuke who was part of the design team for the system. He told me that axle/wheel alignment is the main issue when a side to side weight bias is present and the purpose behind the Correct Track system. The system allows for adjustment in 1/4" increments to keep the axles/wheels aligned with the king pin. Here's a link to more information on it...
http://lci1.com/correct-track-ii
I'm guessing what the loaded weight bias is now as I haven't got a that weighed but it's probably around 900# or more. I had the Correct Track alignment checked while at the Owners' Rally in Elkhart last Sept and all measurements were within the allowed 1/8" tolerance. I would suspect over time that may change as the heavier side springs start to lose the arch. We've got 5000 towing miles on the camper now and it tows great.
Dave