First, a very important thing to understand is that your air springs do NOTHING to help balance your load. The basic concept one needs to be concerned with is weight distribution, i.e.:
- how much weight is on the axles
- how much weight does my TM and TV weigh individually, and my TM and TV weigh combined
You cannot exceed the weight ratings of any of the axles, the individual weight ratings of both your TM and TV, the gross combined vehicle weight (GCVW?) rating, or the tongue weight rating of your TV. Furthermore, if your rear axle is weighted too much relative to the front axle, even if it's within its rated limit, the front of the vehicle points upward. That makes your headlights point upwards, which air shocks can fix, but most importantly, it also reduces your steering control, which air shocks do nothing to fix.
So while your TV may look great with your air shocks inflated, you still could be significantly overweight or your setup may not be easily controlled while on the road.
Our esteemed moderator, Bill, wrote an excellent write-up explaining what you need to know here:
http://www.trailmanorowners.com/foru...ead.php?t=2616
Check it out, and then ask more questions.
Dave
EDIT: You almost certainly will need a WDH, even without the motorcycle. I tow with a Sequoia, which is the same platform as the Tundra, don't take a bike, and I use one. Also, your TM is going to weigh more like 4,000 pounds when loaded for camping.