2nd gen - New suspension/leafs kit for towing Canada - need advice

I live in Quebec (Canada). I had a little surprise when I changed my winter tire. I have a broken leaf on each side. I could see on several discussions that it happened to many people at this place of the leaf's pack.




I was already planning to increase my capacity this spring because I want to buy a travel trailer. I was just thinking of adding a Timbren kit.

With this surprise, what is my best option since I will have to change the leafs anyway?

1. Replace with a standard kit and add a Timbren kit (or other brand if you advise me another)
2. Replace with a stronger kit with more leafs (any suggestion of strong kit?)
3. Replace with a stronger kit with more leafs and add a Timbren kit

Here are my needs for my Tacoma 2013 SR5 4door:
-Preserve ride quality without loading
-I have a shell
-In summer, tow a travel trailer (5000lbs) on weekends. The bed will obviously be filled with camping gear too.
-In winter, tow snowmobiles.
-I live in canada in a region where winter can be -35 celcius degree (-31 fahrenheit degree). Can a Timbren's rubber deteriorate?
-As we can see in the photos, the salt from winter roads brings a lot of rust. Are there any leaf brands better than others at this level?

I am not interested in an air bag kit because I don't trust it in winter.