I have a large home made cargo carrier that goes into the receiver hitch. It's quite large at 5x3. I am building a trap box onto it. Empty weight I'm guessing is about 250 lbs with everything. With traps/animals I could easily see another 250.

Does anyone know what the capability of this vehicle is? I can't really find anything on it. I don't think trailer tounge weight applies? It's a v6 with 3rd row seats if that makes any difference.

I wanted plenty of room, but I'm worried I may have made it too big. Basically 2 sheets of 7/16 osb, and 12 2x3x8's. My estimate on the carrier by itself is close too 100lbs.

I think trailer tongue weight would be a good place to start, basically you are putting weight on the back of the rig outside the 4 wheels. It acts like a lever on the rear of the vehicle so tongue weight limit would be a good suggested starting point.
sounds like your cargo carrier is going to be heavier than your rig should carry without messing with the driving dynamics.

^^^^Tongue weight is what you need to know check your owners manual or look online. My guess is less than 300#.