In 2010 we travelled 25,000 kilometres in our Burro
, and for most of that time (4 1/2 months) we had our two cats with us, until one disappeared in San Antonio. They travelled in a hard-sided pet carrier anchored between the seats of our truck, and wore harnesses the whole trip, so we could clip leashes to them when we were camped.
At night, they roamed free in the trailer and stole the covers so often we would up using two comforters so we got some too. But having left an earlier cat for about six weeks, we know these guys were much happier with us than without us.
We now have three cats and are planning our first trip with them in about three weeks time. We have a new tow vehicle so have opted for a soft-sided carrier to haul them in. They'll be cozy in there, but the two young ones sleep in bundle anyway, and the older cat (the long trip veteran) seemed to prefer close quarters last time out. Hopefully all goes well, and there are many people who travel with their cats. There was an artist on here (haven't seen a posting in a while) who full-timed with his feline friends.
Good luck with your travels.