Your GVWR can not be 3500 since the curb weight is over 4000.

'06 SV6 Manual
Maximum trailer weight is calculated assuming only the
driver is in the tow vehicle and it has all the required
trailering equipment. The weight of additional optional
equipment, passengers and cargo in the tow vehicle
must be subtracted from the maximum trailer weight.

05 Montana Manual
How heavy can a trailer safely be?
It should never weigh more than 1,400 lbs (630 kg)
with up to six occupants in the vehicle or more
than 2,000 lbs (900 kg) with up to two occupants.
If you have the optional trailer towing package, your
vehicle can tow up to 2,900 lbs (1 300 kg) with up
to six occupants or up to 3,500 lbs (1 575 kg) with
up to two occupants. But even that can be too heavy.
It depends on how you plan to use your rig. For
example, speed, altitude, road grades, outside
temperature and how much your vehicle is used to pull
a trailer are all important. And, it can also depend
on any special equipment that you have on your vehicle.

We had an Oldsmobile Silhouette with the same specs that we used to tow a popup for a short period of time.  It was the limit for what I felt it could comfortably tow with just my wife and me.  IMHO it is not going to be a suitable TV for anything with a large frontal area.  Will it move it down the road? Probably.  But factor in hills, wind,  visibility,  and a soft rear suspension and you are setting yourself up for some real pucker moments.  When we bought our 183 Roo we towed it with our Trailblazer and it was taxed power wise, and its on the light side of a lot of hybrids out there.  Sorry to be a buzz-kill.

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