Timbrens or hellwig helper springs

Hello, I have an 09 v6 4.0 2wd tacoma and want to tow my 19ft. TT 4k dry weight. I moved it a couple times. Too much sag. Im thinking hellwig helper springs?

 

I had the helper springs for about 8 years. They helped a little but eventually still got sag in the rear leafs and hit the bump stops all the time. The stock leafs just aren’t great so I upgraded to HD leaf springs from general spring and they are night and day better. Don’t have any experience with Timbrens though.

 

How often do you tow and is that the only time you have significant weight? Airbags would probably be a better option and won't affect the unloaded ride quality.

 

I tow few times a year. Was worried if truck would ride rough with the helper springs..