Some states do have a taxable weight. CA is one of those.
The most strict interpretation by the weight police here (not to be confused with the real police) is to stay under your GVWR. Most people here are over their GVWR either on purpose or accidentally.
If you go with axle ratings, just remember that your brakes aren't necessarily designed to handle the extra weight. They may or may not, but consider more stopping distance.
In any case, you need to go to a scale to find out how much room you have. In my heaviest loaded trip, the scale tickets like the following one will show how much you have on each axle. BTW, my truck is rated for 14500 and also includes axle ratings on the sticker.
Either way, your TC will likely be heavier than you think when you load it. Many here will suggest you should add 1000-1500 to what the camper says by the time you add water, etc, and your stuff. I do carry a lot more now that I have a F450, but I was able to carry the same TC on my previous truck with a SRW. It had a GVWR of 11400. I'm sure I was over, so I ran 19.5s on that SRW to make sure I wasn't over the tire ratings. Stopping is night and day different when the truck is designed to handle the heavier weight and heavier trailers like my F450 is.
'10 Ford F-450, 6.4, 4.30, 4x4, 14,500 GVWR, '06 Host Rainer 950 DS, Torklift Talon tiedowns, Glow Steps, and Fastguns. Bilstein 4600s, Firestone Bags, Toyo M655 Gs, Curt front hitch, Energy Suspension bump stops.
NRA Life Member, CCA Life Member