I don't believe you can massage the numbers enough to do it. While the "empty" tongue weight is actually 400 lbs (according to the website) you will find that with battery and propane, you will be closer to 475 lbs. Add to that the fact that you'll need 12-13% of total TT weight as tongue weight for proper towing and you are looking at a more realistic tongue weight of 520 lbs. and probably at tad more. You then need to account for the weight of your WD hitch, ~100 lbs. You are looking at dropping the equivalent of between 500 and 650 lbs into your RAV 4's luggage area. Your RAV4's vehicle loading is ~1000 lbs max. and that doesn't account for the weight of any options or passengers. My guess is that you'll exceed not only tongue weight, but, maximum loading for the vehicle's frame, suspension and axles.
The trailer itself is rated to 3040 dry weight (that is dead stoned empty) with a max of 6000 lbs. Your quoted weight of 3270 is probably with battery, LPG and options, but, not with even the "required" take alongs; power cable, hoses (drain), fittings (drain) and freshwater supply. The rated full weight for the 189FDS is 6000 lbs. My "guess", is even packing lightly, you'll be a tad over 5,000 ready for the road and that is with empty tanks.
Then we get to the hitch itself... I don't believe the hitch on a RAV 4 is a class IV hitch...most likely a class III or even a class II. You can buy a conversion insert, but, their use will decrease your tow rating by 25%, putting the numbers cited above, way, way over the limit.
I won't even go into "sail area", the amount of horsepower required to overcome wind resistance of the frontal area of the TT while going down the road or the small wheel base of the RAV 4.
I think, if you look at, and talk to folks, about towing with a RAV 4, you will find that it is designed for towing utility (small) trailers, small boat or Jet-Ski trailer or bicycles; not for hard sided TTs. You may be able to tow a pop-up, if kept small, but, IMHO, the RAV 4 trying to tow something as large as the 189FDS is a no-go. Sorry...