Lawrence,
On most Beaver coaches, especially in the SMC era of production, the axle weight is not evenly divided between the right and left tires on the axle. I have seen over a thousand pounds difference between the right and left tires on the same axle. So since you are taking the axle weight and dividing it in half to get your tire loading, you are very probably overloading one or two of your wheel locations by using the minimum allowed pressure on the chart. That is the reason that all RV tire safety sources recommend weighting each wheel location instead of each axle location. However, that being said, since you have a 2003 Monterey that probably has a rear radiator and a front mounted generator, I would not expect more than 2 to 400 lbs. difference from one side to the other.
Gerald