I have not done it for a caravan but I am doing it for my Volvo right now. As you say, it's extremely technical and what's quite fun is that I am supposed to supply "a simplified description" of the vehicle. The "simplified" description is in fact 4 pages of highly technical stuff, half of which I wouldn't even understand in english or even my own language. They require this, despite the fact that Volvo France has provided me (and indirectly them) with a very detailed description of the car, and of course this car model is massproduced and sold also in France, so there will be NO surprises whatsoever, but the document is still required... Should I make a misstake on any of the points in the 4-page document, I am sure (but only guessing) that it would delay the entire process by weeks and I'd run the risk of having to park my car until all the red tape has been cleared.
My insurance has been great though and so has Volvo. They have given lots of assistance!