While the hitch is rated at 400 lbs, the use of a WDH does not increase either tongue weight or towing weight capacity. You are still limited to 350/3500 lbs.
That said, I've been happy with the combination, although it does take some planning on where you are going to put what to keep the tongue weight under 350 lbs if you have the same options I have - Dual Propane, Front Storage Box & Electric jack. Loaded for a 5 month trip my Escape 17B weighs 3020 lbs without the stuff in the refrigerator (a sad story you can read about on my Web Page
) and a tongue weight of 340 lbs.
I installed a Prodigy P3 controller along with a Rear View Safety camera system for both the trailer & the RAV4. I don't have or need air bags - the weight distribution hitch as set up by Reace keeps the rear of the RAV4 within an inch of the unloaded height.
Just a note - here in the US the tow package does not include the wiring for the trailer lights. Toyota sells a "kit" that consists of a 4 way trailer connector, the wiring to run to the front of the vehicle with a connector that matches a receptacle under the steering column. If you can get someone to run a charge line, brake line, and the lighting connector kit for you at any reasonable price, it is worth it. You need to remove & replace all the driver's side paneling, crawl under the dash & hunt for the receptacle, install fused wiring for the charge line & controller, etc.
I did it myself (and ran the video cable for the rear view monitor at the same time) and it is a good day's work.
A web page that I found helpful for installing the controller & charge line as well as a link to Toyota's trailer lighting wiring instructions is here
As to driving out to pick it up, that's a great idea. I did it last April
& continued on for a 18,700 mile trip.