I don't think there is a quick and easy way to be honest mate.
For a start, the trailer/caravan will need electrics, so these will need to be supplied from the car.
Normally to fit a towbar you have to remove the rear bumper, remove the support bar, and bolt the towbar in place of the support bar, then refit the bumper. But by doing this you normally have to cut a hole in the bumper for the towbar to go through

So technically there is no 'temporary' way.