You may have a sticker in your motorhome that will tell you the cargo carrying capacity to know how much reserve capacity you have. (I have on the past 3 class C's). For your trip it's important that you are not overweight.
Your passengers based on the average will be 1,100 pounds just on their own. You will probably have at least another 700 pounds of cargo spread across these passengers. (Food and other gear). It adds up quickly. Teach folks to pack very light and bring only what is absolutely needed.
If this sticker is missing, you will find a sticker at the door pillar on the driver's side door that will show the different axle weight ratings. Don't exceed any single axle weight! You can go to a scale and have it weighed, first the front axle, then the rear axle and the whole vehicle to get a sense of what capacity you have while empty and present axle weights. CAT scales are available at many truck stops. In Oregon, the scales at closed weigh stations are still left on (free). Some other states do as well.
This is a basic article that may be of value. http://www.rvbg.com/Articles/?id=1981639
It is quite common to have extra capacity still available on the front axle but to be near to capacity on the rear duals even before you have loaded cargo.
With that many people going, you will probably need to keep your water tank empty or close to it.
Many people drive their motorhomes overweight on an axle. It's dangerous to do so. You could add air bags such as those from Firestone to improve ride height but they don't increase load capacity of the axle.
Many others will have added real world advice, including suggesting that you can drive over the recommended weights. I don't recommend it. You have the life of 7 folks in your hands.