I won't get into too many details discussed here, but my camper actually unweights my front axle by 150lbs... I am still within my rear axle ratings though. Still quite a bit over GVWR, so you won't see me throwing stones.
I think you'll find most TC's are 90%+ on the rear axle. 40% on the front is being rather ambitious. Say you had a regular cab truck, I could potentially see more weight being put on the front axle due to the front axle being closer to the front of the truck box but not anywhere close to 30 or 40%. This is where COG really comes to play. The nose of the camper is really just an airspace with a couple small cabinets and a matress. The rear 1/4 of the camper is just as heavy, or heavier. You'll have more framing becuase of access door (for dump valves, genny compartments etc), dinette, kitchen cabinets. The rear of the camper has a lot of action happening, therefore quite heavy compared to the nose which extends over the cab.
You're doing the right steps, go weigh the truck and then go weigh the truck and camper. I'm sure you'll be shocked to see the numbers. I had a weight in mind (which was still more than Bigfoot stated) and the real life weight was significantly higher. Going and checking weights will be the best way to proceed.
Again, I'm all for going over GVWR but just keep in mind the rear axle, I think that might be your weak link at the moment. Good luck.