I agree with the half a pig = about half a day including jointing, putting bacon into cure and hams into brine...
Caroline1- before I had a pick up truck and was transporting in a car, I used brand new tarpaulin or have also used thick (new) plastic sheeting. If you're worried about space but want to do some home butchery ask them to cut each half into primals which will be fine in a car with seats pushed flat. They may even put the primals into a large plastic bag for you if you ask them.
MarthaR