How do I calculate all this with a full tank of fuel?
Other info that might be helpful for you is that we camp for bi -annual one month trips. so we don't carry that much. But we do travel mountains of Colorado and the Smokies.

Well i'm sure glad to be able to talk to you guys. Sounds like my tire, breaking and suspension capacity would be stretched to the limit.

Yeah given you said you were concerned about being overweight, and you had to replace suspension parts in a previous rig I don’t think you’ll be comfortable.

BergieClan , welcome to the forum and congrats on your soon to be new trailer. I have a 390 RK solitude which has a front and rear basement. This allows me to shift weight front to rear and vice versa as needed to keep my weight within my truck's capability. I am towing with a 2015 Silverado 3500 single wheel truck. I am within 200 pounds (under) the trucks limit. This is loaded with passengers, full fuel and provisions for two weeks, and more than 1/3 but less than 2/3 tank of fresh water; other tanks empty. The basement areas have mostly air in them, as we do not full-time. A couple of chairs, small pellet smoker, small tool box, items to hook up trailer, portable satellite dish, etc. This all adds up to weight, no matter how much empty space is there. To answer your stability question, there are no issues there. The combination is very stable going down the road, and unaffected by wind or passing trucks and the like. Earlier, I mentioned some weights. I obtained these by going to a truck scale, and paying to get axle and total weight of my combination. I know exactly what I weigh. I do this twice a year, or anytime we do a significant modification to furniture or add something heavy to the trailer (like a laundry center). You just can't know what your weight actually is until you're hooked up, loaded, and on a scale. But my personal (experienced) opinion is that your truck would be better suited to a Reflection than a Solitude. Am pretty sure you don't want to hear that, and I am sorry if that is the case. But we all have a responsibility to ourselves and the rest of the motoring public to be safe. You're going to need either more truck, or less trailer.