There are a lot of Class C's that are at or near their GVWR ratings empty, as you have found in your case. There is nothing you can do to overcome this legally. The only people who can increase your actual GVWR legally are the factory or a licensed up fitter who can issue a new federal weight sticker. It is highly unlikely you will have any luck with either of these possibilities due to liability issues. You can add aftermarket options to mitigate your weight issues, but as you have already stated this will still not make you legal. Sorry I don't have a better answer for you.