Yes, you would have 805 lbs of rating left to put the downward weight of the trailer tongue onto your vehicle. However, you will need a Weight Distributing Hitch (preferably with sway control) onto your vehicle. The weight of that hitch assembly (approx. 100 lbs.) is also subtracted from your payload. Hence you now have 705 lbs. for that downward force or tongue weight...but, the WDH has shifted a percentage of the tongue weight to both your front axle and the trailer's axles. An estimate of 20% could be used. Using that distribution mark, your vehicle can now operate with a tongue weight of 850 lbs.
If you estimate the trailer's tongue weight to be 13% of the trailer's weight and use the 850lb number, you should be able to pull a trailer within the vehicle's ratings of around 6500 lbs. That is 6500 lbs. including all you add into the trailer and the weight of the trailer.
Besides running the tow operation right to the ragged edge of the ratings, there is also the handling to be considered with a shorter wheelbase vehicle and a longer trailer. If you are new to towing, this is harder to explain but simply, a longer trailer can lead to the tail wagging the dog. I would suggest you keep the length down to 24-26 ft. and try to find an unloaded trailer weight of 5000 lbs. You will be much happier traveling and the vehicle won't be pushed to the edge.