Towing on a trailer is not for everyone for various reasons. There are distinct advantages and disadvantages to each method. The cost is probably close either way depending if you use a supplemental brake. If you don't use a supplemental brake then the 4 down method. If you use a supplemental brake then the set up time is probably close both ways. We tow both ways so have the advantage of comparison. We prefer to tow on a trailer as we have an A class motorhome and all but about 5 feet or so of the trailer stores underneath the rear of the motorhome so storage is not an issue. If you have a 2 axle trailer though it will stick out another 3 or 4 feet. The biggest advantage of course is no wear and tear on the car and of course the ability to back up or park anywhere you want as you can literally parallel park the combo anywhere...and we do.
Here are a couple of pics. The first one is ours. The second is a friends. Home this helps those in the decision process. There is no one correct way. Pick what suits your needs.

