Towing trailer cross country

Hello everyone first time user of this forum. I have a 2005 Toyota Tacoma Prerunner 4 X2 only modifications are a K&N intakea ... Im towing a trailer from California to texas ... trailer weight puts me at three thousand pounds with nothing in it let the wife is loading it full of everything as anyone could expect.... plus I need to load my truck with all my tools if I had to guess it would probably be $1,500 to 2000 extra pounds above towing capacity... it has sway bars for the hitch and I'm installing airbags for the suspension ...my major concern is if the transmission and engine will hold up to it... any suggestions on modifications... anybody got any help for me please and thank you

 

You don't mention it, but I would ensure I had trailer brakes.