Many members here are tired of my rant about overloading little trucks but here you go: I'd recommend something like Deaver Springs, no airbags please. Though you are seriously overloading your truck and braking performance will be near dangerous (actually, it will be dangerous), at least with strong leaf springs you are putting the greatest chassis stress where the chassis is strongest and for where it was designed. The problem with any of the airbag designs is that they put the stress on the chassis right in the center of the chassis archway over the rear axle. The structural engineers designed the chassis for expanding stress at the mounting locations of the leaf springs, this is a force that wants to stretch or straighten the arch, for which it is braced. Bags reverse the force, into a force that wants to do the exact opposite, it becomes a force that wants to fold the arch/bring the spring mount points closer together. It is the exact opposite for which the chassis was designed. Yes, you will find others who report thousands of miles trouble free, but those who have had problems, have had
really big problems.
Sorry, I have a real problem when people overload vehicles past legal limits. It is dangerous for others on the road and should you be in an accident and someone is hurt you will be hit with negligence which can cost you everything you make the rest of your life. More than one member here has had near deadly accidents by poor braking in emergency situations and switched to a full size truck. Losing a family member or someone else losing their 6 year old on a bicycle because you could not stop in time is a real bummer.
Here's an idea. You say you are using it as a daily driver. Does that mean a commuter car? There are leases on electric Chevy Sparks, Nissan Leafs and Fiat 500 EV's that are only $199 per month. You pay for zero gasoline, maybe $20 to $40/month in electricity, so vs. your loaded Tacoma getting 15 mpg, the $200 is cheaper! It will be a more peasurable drive, a safer drive, and works out t be a free car! That way your overloaded Tacoma will see less travel time you are greatly reducing its wear, your tire wear and risk at a dangerous accident.
http://www.fiatusa.com/en/2013/500e/
http://www.nissanusa.com/electric-cars/leaf/
http://www.teslamotors.com/