Rear suspension recommendations

I need some advice as to my rear suspension. 2017 4runner, bilstein 6112 leveling kit up front and 5112 rear shocks w/stock springs.
When Im towing my boat, the rear sag's down a bit and also since installing the 6112's and new springs up front, the front is nice and firm....no body roll up front but....I can feel a bit of roll in the rear. Its not bad but it's noticeable if your paying attention.
As far as the vehicles usage, 70% around town, 15% hiway, 5% towing, 10% off road (beach and dirt roads. No rock crawling, no heavy off roading.
Any suggestions would be greatly appreciated!

 

Do you want it to be stiffer all the time, or do you want it to be level when towing, and only when towing?

You've stated the current ride/situation, but not the issue(s) you're trying to resolve, what you want out of modifications.

 

A perfect world....and we know that dont exist. Im looking to keep it level while towing (or closer to level), a but stiffer to minimize the rear body roll (sway), while maintaining the ride something close the ride (not towing) I have now.

 

What about air bags and heavy(er) rear sway bar? You can inflate the bags for towing to keep the sag to a minimum and run them at low pressure all other times?

 

This is exactly why Toyota engineers made the 4R with front end rake. To be level when towing. You've taken that out, now the ass end "appears" to sag under load. Your best option now is coil spring airbags.

 

^ This.

Rake is not a bad thing imo.

If you like your stance and ride quality where it is I'd recommend airbags for towing specifically.
Or you could get stiffer springs and live with some usable rake. The Dobinsons C59-323 come to mind for your application. They are about the stock height but a 220lb rate (stock I believe is 150lb)

https://exitoffroad.com/product/dobinsons-1-to-3-5-build-a-kit-toyota-4runner-5th-gen/
https://exitoffroad.com/product/dob...l-springs-for-lexus-gx460-and-toyota-4runner/

 

Also for loading up the cargo area. It doesn't have the same impact pound-for-pound as tongue weight, but it still matters.

 

Air bags are definitely a strong possibility but I also seen some posts about sumo springs. Anyone have any thoughts or experience with those?

 

Those 220lb springs may solve the problem as well

 

Except the heavier springs will impact the ride 100% of the time. You won't have the same ride you do now.

 

Eibach rear springs may be what your looking for 1" of lift and a 205lb spring rate. Dobinson also what's "stock height" springs but with a 220 lb spring rate.

Oem spring rate is 160-180lbs

 

A quick follow up on this. I ended up installing air bags. Installation was easy, I think it took longer to get the floor jack out along with jack stands and tools. I cut the old rubber bump stops with a band saw which took about 10 sec each. Ive been playing around with the pressure to find the sweet spots. Looks like 16 psi unloaded, 18 with some cargo, and 24psi towing the boat.