I would like to suggest sacred haven to be added to the (rather thin) paladin spell list.
dndtools.net/spells/spell-compendium--86/sacred-haven--4119/I presume some adjustments would have to be made (I suspect the ranged lay on hands-effect simply may not be feasible), though presumably it should be possible to do the first parts at least. My suggestion would be to implement it as a party-wide +2 dodge AC and the effects of Uncanny Dodge I.