Towing Limits?

[Bender]

Edit: Mods can delete this post. I found a ton of info on my VW boards about towing, turbo wear, trans, etc. Thanks!

I have a small 11.5' aluminum boat that I got about a month ago, did a bunch of work on it, and it has been good. But there are a lot of larger lakes around here so I need a bigger boat. One of my friends has a 16' Sylvan with a 40HP Johnson for sale and he will give me a really good deal on it.
The question I have is I am not sure how much longer our company truck will live (230k+ hard miles on the old GMC) so I am thinking about towing with my car. VW does not suggest any towing and voids your warranty if you screw something up from towing, so I want to weigh the risks. I don't plan on towing long distances and the boat weighs about 1000 lbs.
What can happen from towing something? Premature brake wear? What else?

The car is a 2005 VW turbo diesel, 1.9l. 100HP and 177 lb/ft with elec. diff lock, traction, all that so getting it out of the water shouldn't be too bad. Also a nice galv. roller trailer is included.