Four wheels down is much easier. NO you cannot back up four wheels down - tow bar damage and tire damage can occur as the car will not track properly in reverse. We see people use dollys and trailers all the time and are amazed at how much longer it takes most to get ready to depart or unhook on arrival. You also need space at your site to park the dolly/trailer.
With a little practice the four wheel down setup is well under five minutes start to GO. Unhooking maybe two minutes......... Sadly, few new automatic cars are now four wheel down towable.
Best wishes for happy trails whatever you decide to do.