Extra Transmission cooler needed?

Hi all.
I own a 2000 z-24 with 105000km on it. I recently started towing my dirtbike to the tracks to race as i sold my pickup. (1.5hr away.) The trailer must weigh about 300lbs and the bikes are 210 each dry + equipment, fluids n fuels. (2 bikes as i usually take a friend and his bike too)

Now although it seems to haul pretty good and have no problems yet, a friend who owns a towing company told me that it is essential to get an inline tranny rad to fit into the grille somewhere to aid in cooling the tranny. (not much room in the cav grille)
Any input on this anyone?

Hi there. New here. I think the rule goes... If you're pulling more than the rated capacity (1000lbs on your cavy 2.4) then you should absolutely put in a tranny cooler in front of your rad. you sound like you're close, so unless you have problems i'd leave it alone for now. But don't go on my word cause this is an uneducated reply.
Good luck man.