The RX350 Tow package includes an engine oil cooler, HD alternator, and HD fan, with the transmission cooler and HD radiator. Not easily or cheaply retrofitted.
Perhaps you could contact Lexus, and with your VIN number, get a copy of the build sheet, to see if your car is equipped with the Tow Package.
2012 Jay Flight 19RD
2010 Tundra TRD DBL Cab
1 Spoiled Dog