Wanted to share my experances towing with the Tacoma, as I see a lot of mis-information floating around this section and more "Can My Tacoma Tow This Trailer" threads. I would highly recommend you read the Tacoma Towing Bible, as this helped me out. We started RVing approx. 2 years ago. I used then, as I use now, my 2010 Double Cab TRD Off Road Tacoma. We first started out with a Salem Cruise Lite 195bh, a single axle, travel trailer. Empty weight was around 3000 pds. Even then, people where telling me that this was "too much trailer" for the truck, when in actuality, it really wasnt at all.
There are a few realities and considerations you must make prior to considering the purchase of an RV, mainly who and where you will be using the trailer the most. Myself, I have a family with 2 young kids and a wife.... We mainly go to RV parks or national parks, as the vast majiorty of those who own travel trailers do. This is important, as if you arent going to the back country, you can subtract water weight from the towing equation. Most National Parks offer some form of water at their RV sites(check prior to going). Water accounts for a massive portion of loaded trailer weight. It is for this reason I see many people get less trailer than they can, dispite the fact that they may never fill their fresh water tank.
A few realities you must consider about our beloved truck, the Tacoma. I love the Tacoma, it is a very capible truck, however, it wasnt built for towing. It can and will hold its weight and tow, however, expect gas mileage to be somewhere around 8-12 mpg... If you tow often or extended distances, this truck may not prove economical. Further, I have noticed little difference (if any at all) in fuel economy from towing an approx. 3600 pd trailer to an approx. 56-6000 pd trailer.
Trailer brakes are a MUST, and another thing I would highly recommend is a quailty weight distribution hitch. It makes all the difference in the world.
I currently tow a 27 foot TT that is 4060 dry. It actually drives better than my former single axle trailer and I notice little difference from the truck.