As for the auto tranny, turn the overdrive off when towing. Definitely get a tranny cooler, if you don't already have one.

If you are planning on towing somewhere close to 5000 lbs., be prepared to go really slow uphill. The 3.3 is very underpowered.

People on this and other boards have suggested electric trailer brakes and a weight distributing hitch for that kind of load. IMO, an AAL or heavy duty spring pack is necessary if you plan on towing and hauling gear / people at the same time.