quagmire with '11 tacoma w/o tow package about to tow

I have a '11 tacoma without tow package. I got a good deal on it 500 miles away thus I couldn't resist. I figured I could put an aftermarket transmission cooler -as well as maybe oil cooler- on after purchase. I've talked to corporate and they are telling me if I modify in any way, warranty is void and I am on my own.
I am pulling an r pod 177 which weighs about 2600 pounds. I'll have a couple 2000w generators and a few other items thus 2800 or 2900 pounds max pulling. I'll also have a 300 pound scooter in the back of the bed as well as containers of food etc.. I will be pulling with my Tacoma on many trips on all terrain (whatever is found in this vast country as well as Canada).
I feel I may be damned if I do, damned if I don't; thus, should I just say f#%* the warranty and do the modifications anyway or will I be fine with the specs mentioned? I've read the posts in the towing section and plan to: drive 55 MPH all the time, drive in 4th gear (or 4 slot) (and third when in the mountains, right?), keep the weight down and under the recommended 3500 pounds, will have electric brakes for my camper, keep up on maintenence issues, etc. I know I'll probably put these items on after the warranty but I do not wish to damage -long term- my engine or transmission. Any thoughts. I've also thought I could put it on and maybe they would not even notice.

 

Also, as long as I do not allow the transmission to "hunt" for the right gear (i.e. overdrive or 5th) over and over again via keeping it in 4th (I have an automatic), the transmission would not overheat, right? I also thought maybe putting synthetic (without corporate knowing) in the transmission would prevent breakdown of fluid, any thoughts? I appreciate any knowledgable feedback from this community.

 

Certainly a good transmission oil cooler is reccomended, (B&M, Hayden, etc.) I am not certain an engine oil cooler is needed, but in hot weather for sure it cannot hurt. You may want to consider add-a-leaf, helper springs or air bags, depending on how much your rear drops under load. None of this WILL void your warranty.

 

Why not just have the dealership install the tow package? Your warranty would still be good, your towing weight allowance would increase, and you'll have some peace of mind.

 

Shifting from gear to gear isn't the only way the transmission builds heat. Once you're cruising, the torque convertor locks so it mimics a manual transmission, when you step on the gas, the torque convertor unlocks and this can build a lot of heat in a hurry. If you plan on towing frequently, I'd look into a transmission oil cooler.