Help choosing something like Cougar

Thanks so much everyone for your detailed and clear explanation. I can't believe the RV dealers we went to didn't provide the same. You are right that the towing capacity is calculated based on just one 150lb person driving. After I did the math you provided, I ended up with just a 5100 lb towing capacity. We just towed a trailer 3 hrs each way that's 6875 lb dry (not counting the weight distribution / sway hitch). I don't think my family will be happy with anything smaller than that trailer, so it seems I now need to look for a tow vehicle as well.

So, let's ignore the towing capacity for now and just focus on figuring out which TTs we should be looking at. Can folks help me with that please?