2007 Suburban Z71 towing question

I have to assume you have a 1500 Suburban? Have you weighed everything yet? Before you go spending ambunchmof $$$ on stuff you need to load up like your going camping and get to the scales. My guess with family on board your overloading the Suburban. If thats the case, no amount of money is going to stop the self destruction. BTW once you have towed that hot it is highly likely the trans coolant is toast. Get it serviced before it costs you a transmission rebuild.
Also, towing faster than the trailer tire manufacturers rated speed is asking for another disaster.