We did this some years back with Haven at Devon Cliffs resort. You book a mobile home that sleeps say eight and give names of the group, say six of you,and give two falso girls names on the form. The cost is per van (or at least it was then) so you just divide the cost. Only one needs check in and collect the keys and passes etc, though some degree of brass neck is required "the others are following in anothe car " etc. They have bars/discos on site and its not too far from Exmouth town for a bit of variety.
We did it three years on the trot (many years ago now) and whilst it's not Ibiza we certainly all had a whale of a time.