Take what will fit, and buy the rest there.
If it is only for a year, why not leave your stuff in storage and get some cheap stuff to see you through the year. You could easily utilise something like Craigslist or Goodwill stores. You'd probably spend as much as you would with the trailer etc., without all the hassle.
Although we never had to make a large move, even when we went camping for two or three weeks with our five children we never carried anything on top of or at the back of our VW Microbus (commonly called a Kombi). Tents, tarps, ropes etc was all packed under the seats. The rest was packed behind the back seat on top of the engine, secured with a net so it could not become missiles in a mishap. What did not fit, did not come.
Lifey
One thing I just remembered.
My daughter and her husband and their three children make regular international trips. One thing she does to prepare the children, now aged 8, 5 and 3, is with books and stories. She goes to the library and gets out book from the children's section, which deal with travel and with the places they plan to visit or the the things they plan to do. Even about the 14 hour plus flight.
These then become bedtime reading for months leading up to the departure. Even the youngest talks excitedly and with anticipation of the trip. Story time at home is handled likewise, with stories the parents have read or heard. I am sure you will find your daughter would be interested in age appropriate information about the forthcoming trip.
Lifey
More about ice, coolers and what to put in a cooler when on a road trip!
There's an ongoing discussion about using ice or not on road trips -- that you might find helpful -- Personally, I've not used ice in over a decade -- but more on the topic here.
Of more importance -- here is a great, quick-reading article about what to put in your cooler when on road trips.... (contributed by Dennis Weaver).
And a general list of cooler tips contributed by Sofia Romano.
Mark