What is the best Tacoma bed rack for roof top tent?

Ideally, that would be a bed rack that has a high weight load rating such as the RCI bed rack, OVS Freedom bed rack, Leitner ACS Forged bed rack, and even the Tuff Stuff bed rack.

What is the Toyota Tacoma bed rack weight limit?

That differs from rack to rack. Some have a weight limit of around 400-500 lbs while some can withstand an impressive 1400lbs of weight load!

How to install a Tacoma bed rack?

There are some bed racks that require drilling in order to be installed. Some can be mounted using clamps or even rail brackets that will secure the bed rack to the truck bed rails.

Is there a Tacoma bed rack that works with tonneau cover?

Yes there is! That would be the Front Runner Slimline II bed rack with RETRAX cover, or the Leitner ACS Tonneau, or the RCI with the tonneau cover adapters.