Jetta TDI with a double clutch transmission should work well too - fast shifting transmission and lots of low end torque should be ideal for this purpose.

NOOOOOOOOOO !!! ;-) VW does not recommend any towing with vehicles using DSG transmissions. While I agree that the TDI equipped (Turbo Direct Injected Diesel engines) are ideal towing vehicles - I have one myself - I would always opt for the straight manual 6-speed transmission. BTW, in Germany, the Jetta TDI station wagon is certified for towing trailers around 1,700kg if they are equipped with a surge brake. That should take care of most glider/trailer combinations I know.
For the long hauls, I use a Passat SW (2L, 4-banger gasoline engine) which only comes with a 6-speed automatic (in the US). I went from SC to Parowan, UT twice now and had no issues. Of course on the steepest and longest climbs, one has to make an allowance for having only 4 cylinders on duty but so what.

Uli