Parking in Edinburgh isn't in with a chance. Morton Hall camp-site is a dead loss right out there as the buses aren't good and last time I used it there were no late night buses.
(RIP Little France camp-site. Far better site only 3m out. Yes Edinburgh had to put its hospital somewhere but they should have replaced the camp-site with a decent one.)
There is an excellent Caravan Club camp-site on the Forth with good day and night buses but they won't take reservations for their small tent area.